diff --git a/INSTALL.md b/INSTALL.md
index e74706d6aa30..af2e844677aa 100644
--- a/INSTALL.md
+++ b/INSTALL.md
@@ -150,9 +150,9 @@ Note that in msys2, Copy is Ctrl+Insert and Paste is Shift+Insert.
     <details>
         <summary><i>Notes...</i></summary>
 
-    >   Note 1: While not shown, msys uses forward slashes `/` instead of backwards slashes `\` as the directory separator.  
-    >   Note 2: If the path has spaces, then the path must be wrapped with quotations, e.g. `cd "Downloads/My Downloads"`.  
-    >   Note 3: Windows path names are case-insensitive so adhering to capitalization isn’t needed.   
+    >   Note 1: While not shown, msys uses forward slashes `/` instead of backwards slashes `\` as the directory separator.
+    >   Note 2: If the path has spaces, then the path must be wrapped with quotations, e.g. `cd "Downloads/My Downloads"`.
+    >   Note 3: Windows path names are case-insensitive so adhering to capitalization isn’t needed.
     >   Note 4: If libpng was saved elsewhere, you will need to specify the full path to where libpng was downloaded, e.g. `cd c:/devkitpro/msys2` if it was saved there.
     </details>
 
diff --git a/src/battle_factory.c b/src/battle_factory.c
index 5d7a199dc300..4543bfbad46e 100644
--- a/src/battle_factory.c
+++ b/src/battle_factory.c
@@ -741,8 +741,15 @@ u8 GetFactoryMonFixedIV(u8 challengeNum, bool8 isLastBattle)
     u8 ivSet;
     bool8 useHigherIV = isLastBattle ? TRUE : FALSE;
 
-    if (challengeNum > 8)
-        ivSet = 7;
+// The Factory has an out-of-bounds access when generating the rental draft for round 9 (challengeNum==8),
+// or the "elevated" rentals from round 8 (challengeNum+1==8)
+// This happens to land on a number higher than 31, which is interpreted as "random IVs"
+#ifdef BUGFIX
+    if (challengeNum >= ARRAY_COUNT(sFixedIVTable))
+#else
+    if (challengeNum > ARRAY_COUNT(sFixedIVTable))
+#endif
+        ivSet = ARRAY_COUNT(sFixedIVTable) - 1;
     else
         ivSet = challengeNum;
 
diff --git a/src/event_object_movement.c b/src/event_object_movement.c
index 29969b1f6b0b..cdd72d668c3e 100644
--- a/src/event_object_movement.c
+++ b/src/event_object_movement.c
@@ -1325,7 +1325,7 @@ u8 Unref_TryInitLocalObjectEvent(u8 localId)
         if (InBattlePyramid())
             objectEventCount = GetNumBattlePyramidObjectEvents();
         else if (InTrainerHill())
-            objectEventCount = 2;
+            objectEventCount = HILL_TRAINERS_PER_FLOOR;
         else
             objectEventCount = gMapHeader.events->objectEventCount;
 
@@ -1641,7 +1641,7 @@ void TrySpawnObjectEvents(s16 cameraX, s16 cameraY)
         if (InBattlePyramid())
             objectCount = GetNumBattlePyramidObjectEvents();
         else if (InTrainerHill())
-            objectCount = 2;
+            objectCount = HILL_TRAINERS_PER_FLOOR;
         else
             objectCount = gMapHeader.events->objectEventCount;
 
diff --git a/src/field_effect_helpers.c b/src/field_effect_helpers.c
index 386c3c76b27b..ac4dac3ecb0f 100755
--- a/src/field_effect_helpers.c
+++ b/src/field_effect_helpers.c
@@ -32,8 +32,12 @@ static void UpdateBobbingEffect(struct ObjectEvent *, struct Sprite *, struct Sp
 static void SpriteCB_UnderwaterSurfBlob(struct Sprite *);
 static u32 ShowDisguiseFieldEffect(u8, u8, u8);
 
-// Used by several field effects to determine which of a group it is
-#define sFldEff    data[1]
+// Data used by all the field effects that share UpdateJumpImpactEffect
+#define sJumpElevation  data[0]
+#define sJumpFldEff     data[1]
+
+// Data used by all the field effects that share WaitFieldEffectSpriteAnim
+#define sWaitFldEff  data[0]
 
 #define sReflectionObjEventId       data[0]
 #define sReflectionObjEventLocalId  data[1]
@@ -44,7 +48,7 @@ void SetUpReflection(struct ObjectEvent *objectEvent, struct Sprite *sprite, boo
 {
     struct Sprite *reflectionSprite;
 
-    reflectionSprite = &gSprites[CreateCopySpriteAt(sprite, sprite->x, sprite->y, 0x98)];
+    reflectionSprite = &gSprites[CreateCopySpriteAt(sprite, sprite->x, sprite->y, 152)];
     reflectionSprite->callback = UpdateObjectReflectionSprite;
     reflectionSprite->oam.priority = 3;
     reflectionSprite->oam.paletteNum = gReflectionEffectPaletteMap[reflectionSprite->oam.paletteNum];
@@ -92,9 +96,7 @@ static void LoadObjectReflectionPalette(struct ObjectEvent *objectEvent, struct
 
 static void LoadObjectRegularReflectionPalette(struct ObjectEvent *objectEvent, u8 paletteIndex)
 {
-    const struct ObjectEventGraphicsInfo *graphicsInfo;
-
-    graphicsInfo = GetObjectEventGraphicsInfo(objectEvent->graphicsId);
+    const struct ObjectEventGraphicsInfo *graphicsInfo = GetObjectEventGraphicsInfo(objectEvent->graphicsId);
     if (graphicsInfo->reflectionPaletteTag != OBJ_EVENT_PAL_TAG_NONE)
     {
         if (graphicsInfo->paletteSlot == PALSLOT_PLAYER)
@@ -111,9 +113,7 @@ static void LoadObjectRegularReflectionPalette(struct ObjectEvent *objectEvent,
 // This is so the sprite blends in with the dark water metatile underneath the bridge.
 static void LoadObjectHighBridgeReflectionPalette(struct ObjectEvent *objectEvent, u8 paletteNum)
 {
-    const struct ObjectEventGraphicsInfo *graphicsInfo;
-
-    graphicsInfo = GetObjectEventGraphicsInfo(objectEvent->graphicsId);
+    const struct ObjectEventGraphicsInfo *graphicsInfo = GetObjectEventGraphicsInfo(objectEvent->graphicsId);
     if (graphicsInfo->reflectionPaletteTag != OBJ_EVENT_PAL_TAG_NONE)
     {
         PatchObjectPalette(graphicsInfo->reflectionPaletteTag, paletteNum);
@@ -123,11 +123,8 @@ static void LoadObjectHighBridgeReflectionPalette(struct ObjectEvent *objectEven
 
 static void UpdateObjectReflectionSprite(struct Sprite *reflectionSprite)
 {
-    struct ObjectEvent *objectEvent;
-    struct Sprite *mainSprite;
-
-    objectEvent = &gObjectEvents[reflectionSprite->sReflectionObjEventId];
-    mainSprite = &gSprites[objectEvent->spriteId];
+    struct ObjectEvent *objectEvent = &gObjectEvents[reflectionSprite->sReflectionObjEventId];
+    struct Sprite *mainSprite = &gSprites[objectEvent->spriteId];
     if (!objectEvent->active || !objectEvent->hasReflection || objectEvent->localId != reflectionSprite->sReflectionObjEventLocalId)
     {
         reflectionSprite->inUse = FALSE;
@@ -172,15 +169,15 @@ static void UpdateObjectReflectionSprite(struct Sprite *reflectionSprite)
 
 extern const struct SpriteTemplate *const gFieldEffectObjectTemplatePointers[];
 
+#define sPrevX data[0]
+#define sPrevY data[1]
+
 u8 CreateWarpArrowSprite(void)
 {
-    u8 spriteId;
-    struct Sprite *sprite;
-
-    spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_ARROW], 0, 0, 0x52);
+    u8 spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_ARROW], 0, 0, 82);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->oam.priority = 1;
         sprite->coordOffsetEnabled = TRUE;
         sprite->invisible = TRUE;
@@ -195,24 +192,24 @@ void SetSpriteInvisible(u8 spriteId)
 
 void ShowWarpArrowSprite(u8 spriteId, u8 direction, s16 x, s16 y)
 {
-    s16 x2;
-    s16 y2;
-    struct Sprite *sprite;
-
-    sprite = &gSprites[spriteId];
-    if (sprite->invisible || sprite->data[0] != x || sprite->data[1] != y)
+    struct Sprite *sprite = &gSprites[spriteId];
+    if (sprite->invisible || sprite->sPrevX != x || sprite->sPrevY != y)
     {
+        s16 x2, y2;
         SetSpritePosToMapCoords(x, y, &x2, &y2);
         sprite = &gSprites[spriteId];
         sprite->x = x2 + 8;
         sprite->y = y2 + 8;
         sprite->invisible = FALSE;
-        sprite->data[0] = x;
-        sprite->data[1] = y;
+        sprite->sPrevX = x;
+        sprite->sPrevY = y;
         StartSpriteAnim(sprite, direction - 1);
     }
 }
 
+#undef sPrevX
+#undef sPrevY
+
 static const u8 sShadowEffectTemplateIds[] = {
     FLDEFFOBJ_SHADOW_S,
     FLDEFFOBJ_SHADOW_M,
@@ -227,22 +224,24 @@ const u16 gShadowVerticalOffsets[] = {
     16
 };
 
+// Sprite data for FLDEFF_SHADOW
+#define sLocalId  data[0]
+#define sMapNum   data[1]
+#define sMapGroup data[2]
+#define sYOffset  data[3]
+
 u32 FldEff_Shadow(void)
 {
-    u8 objectEventId;
-    const struct ObjectEventGraphicsInfo *graphicsInfo;
-    u8 spriteId;
-
-    objectEventId = GetObjectEventIdByLocalIdAndMap(gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
-    graphicsInfo = GetObjectEventGraphicsInfo(gObjectEvents[objectEventId].graphicsId);
-    spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[sShadowEffectTemplateIds[graphicsInfo->shadowSize]], 0, 0, 0x94);
+    u8 objectEventId = GetObjectEventIdByLocalIdAndMap(gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
+    const struct ObjectEventGraphicsInfo *graphicsInfo = GetObjectEventGraphicsInfo(gObjectEvents[objectEventId].graphicsId);
+    u8 spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[sShadowEffectTemplateIds[graphicsInfo->shadowSize]], 0, 0, 148);
     if (spriteId != MAX_SPRITES)
     {
         gSprites[spriteId].coordOffsetEnabled = TRUE;
-        gSprites[spriteId].data[0] = gFieldEffectArguments[0];
-        gSprites[spriteId].data[1] = gFieldEffectArguments[1];
-        gSprites[spriteId].data[2] = gFieldEffectArguments[2];
-        gSprites[spriteId].data[3] = (graphicsInfo->height >> 1) - gShadowVerticalOffsets[graphicsInfo->shadowSize];
+        gSprites[spriteId].sLocalId = gFieldEffectArguments[0];
+        gSprites[spriteId].sMapNum = gFieldEffectArguments[1];
+        gSprites[spriteId].sMapGroup = gFieldEffectArguments[2];
+        gSprites[spriteId].sYOffset = (graphicsInfo->height >> 1) - gShadowVerticalOffsets[graphicsInfo->shadowSize];
     }
     return 0;
 }
@@ -250,20 +249,18 @@ u32 FldEff_Shadow(void)
 void UpdateShadowFieldEffect(struct Sprite *sprite)
 {
     u8 objectEventId;
-    struct ObjectEvent *objectEvent;
-    struct Sprite *linkedSprite;
 
-    if (TryGetObjectEventIdByLocalIdAndMap(sprite->data[0], sprite->data[1], sprite->data[2], &objectEventId))
+    if (TryGetObjectEventIdByLocalIdAndMap(sprite->sLocalId, sprite->sMapNum, sprite->sMapGroup, &objectEventId))
     {
         FieldEffectStop(sprite, FLDEFF_SHADOW);
     }
     else
     {
-        objectEvent = &gObjectEvents[objectEventId];
-        linkedSprite = &gSprites[objectEvent->spriteId];
+        struct ObjectEvent *objectEvent = &gObjectEvents[objectEventId];
+        struct Sprite *linkedSprite = &gSprites[objectEvent->spriteId];
         sprite->oam.priority = linkedSprite->oam.priority;
         sprite->x = linkedSprite->x;
-        sprite->y = linkedSprite->y + sprite->data[3];
+        sprite->y = linkedSprite->y + sprite->sYOffset;
         if (!objectEvent->active || !objectEvent->hasShadow
          || MetatileBehavior_IsPokeGrass(objectEvent->currentMetatileBehavior)
          || MetatileBehavior_IsSurfableWaterOrUnderwater(objectEvent->currentMetatileBehavior)
@@ -276,6 +273,11 @@ void UpdateShadowFieldEffect(struct Sprite *sprite)
     }
 }
 
+#undef sLocalId
+#undef sMapNum
+#undef sMapGroup
+#undef sYOffset
+
 // Sprite data for FLDEFF_TALL_GRASS and FLDEFF_LONG_GRASS
 #define sElevation   data[0]
 #define sX           data[1]
@@ -288,18 +290,14 @@ void UpdateShadowFieldEffect(struct Sprite *sprite)
 
 u32 FldEff_TallGrass(void)
 {
-    s16 x;
-    s16 y;
     u8 spriteId;
-    struct Sprite *sprite;
-
-    x = gFieldEffectArguments[0];
-    y = gFieldEffectArguments[1];
+    s16 x = gFieldEffectArguments[0];
+    s16 y = gFieldEffectArguments[1];
     SetSpritePosToOffsetMapCoords(&x, &y, 8, 8);
     spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_TALL_GRASS], x, y, 0);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = gFieldEffectArguments[3];
         sprite->sElevation = gFieldEffectArguments[2];
@@ -317,15 +315,12 @@ u32 FldEff_TallGrass(void)
 
 void UpdateTallGrassFieldEffect(struct Sprite *sprite)
 {
-    u8 mapNum;
-    u8 mapGroup;
     u8 metatileBehavior;
     u8 localId;
     u8 objectEventId;
-    struct ObjectEvent *objectEvent;
+    u8 mapNum = sprite->sCurrentMap >> 8;
+    u8 mapGroup = sprite->sCurrentMap;
 
-    mapNum = sprite->sCurrentMap >> 8;
-    mapGroup = sprite->sCurrentMap;
     if (gCamera.active && (gSaveBlock1Ptr->location.mapNum != mapNum || gSaveBlock1Ptr->location.mapGroup != mapGroup))
     {
         sprite->sX -= gCamera.x;
@@ -346,11 +341,9 @@ void UpdateTallGrassFieldEffect(struct Sprite *sprite)
     else
     {
         // Check if the object that triggered the effect has moved away
-        objectEvent = &gObjectEvents[objectEventId];
-        if ((objectEvent->currentCoords.x != sprite->sX
-          || objectEvent->currentCoords.y != sprite->sY)
-        && (objectEvent->previousCoords.x != sprite->sX
-         || objectEvent->previousCoords.y != sprite->sY))
+        struct ObjectEvent *objectEvent = &gObjectEvents[objectEventId];
+        if ((objectEvent->currentCoords.x != sprite->sX || objectEvent->currentCoords.y != sprite->sY)
+        && (objectEvent->previousCoords.x != sprite->sX || objectEvent->previousCoords.y != sprite->sY))
             sprite->sObjectMoved = TRUE;
 
         // Metatile behavior var re-used as subpriority
@@ -366,31 +359,28 @@ void UpdateTallGrassFieldEffect(struct Sprite *sprite)
 u32 FldEff_JumpTallGrass(void)
 {
     u8 spriteId;
-    struct Sprite *sprite;
 
     SetSpritePosToOffsetMapCoords((s16 *)&gFieldEffectArguments[0], (s16 *)&gFieldEffectArguments[1], 8, 12);
     spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_JUMP_TALL_GRASS], gFieldEffectArguments[0], gFieldEffectArguments[1], 0);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = gFieldEffectArguments[3];
-        sprite->sElevation = gFieldEffectArguments[2];
-        sprite->sFldEff = FLDEFF_JUMP_TALL_GRASS;
+        sprite->sJumpElevation = gFieldEffectArguments[2];
+        sprite->sJumpFldEff = FLDEFF_JUMP_TALL_GRASS;
     }
     return 0;
 }
 
 u8 FindTallGrassFieldEffectSpriteId(u8 localId, u8 mapNum, u8 mapGroup, s16 x, s16 y)
 {
-    struct Sprite *sprite;
     u8 i;
-
     for (i = 0; i < MAX_SPRITES; i ++)
     {
         if (gSprites[i].inUse)
         {
-            sprite = &gSprites[i];
+            struct Sprite *sprite = &gSprites[i];
             if (sprite->callback == UpdateTallGrassFieldEffect
                 && (x == sprite->sX && y == sprite->sY)
                 && localId == (u8)(sprite->sLocalId)
@@ -404,18 +394,14 @@ u8 FindTallGrassFieldEffectSpriteId(u8 localId, u8 mapNum, u8 mapGroup, s16 x, s
 
 u32 FldEff_LongGrass(void)
 {
-    s16 x;
-    s16 y;
     u8 spriteId;
-    struct Sprite *sprite;
-
-    x = gFieldEffectArguments[0];
-    y = gFieldEffectArguments[1];
+    s16 x = gFieldEffectArguments[0];
+    s16 y = gFieldEffectArguments[1];
     SetSpritePosToOffsetMapCoords(&x, &y, 8, 8);
     spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_LONG_GRASS], x, y, 0);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = ElevationToPriority(gFieldEffectArguments[2]);
         sprite->sElevation = gFieldEffectArguments[2];
@@ -433,15 +419,12 @@ u32 FldEff_LongGrass(void)
 
 void UpdateLongGrassFieldEffect(struct Sprite *sprite)
 {
-    u8 mapNum;
-    u8 mapGroup;
     u8 metatileBehavior;
     u8 localId;
     u8 objectEventId;
-    struct ObjectEvent *objectEvent;
+    u8 mapNum = sprite->sCurrentMap >> 8;
+    u8 mapGroup = sprite->sCurrentMap;
 
-    mapNum = sprite->sCurrentMap >> 8;
-    mapGroup = sprite->sCurrentMap;
     if (gCamera.active && (gSaveBlock1Ptr->location.mapNum != mapNum || gSaveBlock1Ptr->location.mapGroup != mapGroup))
     {
         sprite->sX -= gCamera.x;
@@ -451,7 +434,7 @@ void UpdateLongGrassFieldEffect(struct Sprite *sprite)
     localId = sprite->sLocalId;
     mapNum = sprite->sMapNum;
     mapGroup = sprite->sMapGroup;
-    metatileBehavior = MapGridGetMetatileBehaviorAt(sprite->data[1], sprite->data[2]);
+    metatileBehavior = MapGridGetMetatileBehaviorAt(sprite->sX, sprite->sY);
     if (TryGetObjectEventIdByLocalIdAndMap(localId, mapNum, mapGroup, &objectEventId)
      || !MetatileBehavior_IsLongGrass(metatileBehavior)
      || (sprite->sObjectMoved && sprite->animEnded))
@@ -461,11 +444,9 @@ void UpdateLongGrassFieldEffect(struct Sprite *sprite)
     else
     {
         // Check if the object that triggered the effect has moved away
-        objectEvent = &gObjectEvents[objectEventId];
-        if ((objectEvent->currentCoords.x != sprite->data[1]
-          || objectEvent->currentCoords.y != sprite->data[2])
-        && (objectEvent->previousCoords.x != sprite->data[1]
-         || objectEvent->previousCoords.y != sprite->data[2]))
+        struct ObjectEvent *objectEvent = &gObjectEvents[objectEventId];
+        if ((objectEvent->currentCoords.x != sprite->sX || objectEvent->currentCoords.y != sprite->sY)
+         && (objectEvent->previousCoords.x != sprite->sX || objectEvent->previousCoords.y != sprite->sY))
             sprite->sObjectMoved = TRUE;
 
         UpdateObjectEventSpriteInvisibility(sprite, FALSE);
@@ -473,6 +454,7 @@ void UpdateLongGrassFieldEffect(struct Sprite *sprite)
     }
 }
 
+#undef sElevation
 #undef sX
 #undef sY
 #undef sMapNum
@@ -486,41 +468,42 @@ void UpdateLongGrassFieldEffect(struct Sprite *sprite)
 u32 FldEff_JumpLongGrass(void)
 {
     u8 spriteId;
-    struct Sprite *sprite;
 
     SetSpritePosToOffsetMapCoords((s16 *)&gFieldEffectArguments[0], (s16 *)&gFieldEffectArguments[1], 8, 8);
     spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_JUMP_LONG_GRASS], gFieldEffectArguments[0], gFieldEffectArguments[1], 0);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = gFieldEffectArguments[3];
-        sprite->sElevation = gFieldEffectArguments[2];
-        sprite->sFldEff = FLDEFF_JUMP_LONG_GRASS;
+        sprite->sJumpElevation = gFieldEffectArguments[2];
+        sprite->sJumpFldEff = FLDEFF_JUMP_LONG_GRASS;
     }
     return 0;
 }
 
+// Sprite data for FLDEFF_SHORT_GRASS
+#define sLocalId  data[0]
+#define sMapNum   data[1]
+#define sMapGroup data[2]
+#define sPrevX    data[3]
+#define sPrevY    data[4]
+
 u32 FldEff_ShortGrass(void)
 {
-    u8 objectEventId;
-    struct ObjectEvent *objectEvent;
-    u8 spriteId;
-    struct Sprite *sprite;
-
-    objectEventId = GetObjectEventIdByLocalIdAndMap(gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
-    objectEvent = &gObjectEvents[objectEventId];
-    spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_SHORT_GRASS], 0, 0, 0);
+    u8 objectEventId = GetObjectEventIdByLocalIdAndMap(gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
+    struct ObjectEvent *objectEvent = &gObjectEvents[objectEventId];
+    u8 spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_SHORT_GRASS], 0, 0, 0);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &(gSprites[spriteId]);
+        struct Sprite *sprite = &(gSprites[spriteId]);
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = gSprites[objectEvent->spriteId].oam.priority;
-        sprite->data[0] = gFieldEffectArguments[0];
-        sprite->data[1] = gFieldEffectArguments[1];
-        sprite->data[2] = gFieldEffectArguments[2];
-        sprite->data[3] = gSprites[objectEvent->spriteId].x;
-        sprite->data[4] = gSprites[objectEvent->spriteId].y;
+        sprite->sLocalId = gFieldEffectArguments[0];
+        sprite->sMapNum = gFieldEffectArguments[1];
+        sprite->sMapGroup = gFieldEffectArguments[2];
+        sprite->sPrevX = gSprites[objectEvent->spriteId].x;
+        sprite->sPrevY = gSprites[objectEvent->spriteId].y;
     }
     return 0;
 }
@@ -528,32 +511,28 @@ u32 FldEff_ShortGrass(void)
 void UpdateShortGrassFieldEffect(struct Sprite *sprite)
 {
     u8 objectEventId;
-    s16 x;
-    s16 y;
-    const struct ObjectEventGraphicsInfo *graphicsInfo;
-    struct Sprite *linkedSprite;
 
-    if (TryGetObjectEventIdByLocalIdAndMap(sprite->data[0], sprite->data[1], sprite->data[2], &objectEventId) || !gObjectEvents[objectEventId].inShortGrass)
+    if (TryGetObjectEventIdByLocalIdAndMap(sprite->sLocalId, sprite->sMapNum, sprite->sMapGroup, &objectEventId) || !gObjectEvents[objectEventId].inShortGrass)
     {
         FieldEffectStop(sprite, FLDEFF_SHORT_GRASS);
     }
     else
     {
-        graphicsInfo = GetObjectEventGraphicsInfo(gObjectEvents[objectEventId].graphicsId);
-        linkedSprite = &gSprites[gObjectEvents[objectEventId].spriteId];
-        y = linkedSprite->y;
-        x = linkedSprite->x;
-        if (x != sprite->data[3] || y != sprite->data[4])
+        const struct ObjectEventGraphicsInfo *graphicsInfo = GetObjectEventGraphicsInfo(gObjectEvents[objectEventId].graphicsId);
+        struct Sprite *linkedSprite = &gSprites[gObjectEvents[objectEventId].spriteId];
+        s16 parentY = linkedSprite->y;
+        s16 parentX = linkedSprite->x;
+        if (parentX != sprite->sPrevX || parentY != sprite->sPrevY)
         {
-            sprite->data[3] = x;
-            sprite->data[4] = y;
+            // Parent sprite moved, try to restart the animation
+            sprite->sPrevX = parentX;
+            sprite->sPrevY = parentY;
             if (sprite->animEnded)
-            {
                 StartSpriteAnim(sprite, 0);
-            }
         }
-        sprite->x = x;
-        sprite->y = y;
+        sprite->x = parentX;
+        sprite->y = parentY;
+        // Offset the grass sprite halfway down the parent sprite.
         sprite->y2 = (graphicsInfo->height >> 1) - 8;
         sprite->subpriority = linkedSprite->subpriority - 1;
         sprite->oam.priority = linkedSprite->oam.priority;
@@ -561,19 +540,29 @@ void UpdateShortGrassFieldEffect(struct Sprite *sprite)
     }
 }
 
+#undef sLocalId
+#undef sMapNum
+#undef sMapGroup
+#undef sPrevX
+#undef sPrevY
+
+// Sprite data for FLDEFF_SAND_FOOTPRINTS, FLDEFF_DEEP_SAND_FOOTPRINTS, and FLDEFF_BIKE_TIRE_TRACKS
+#define sState   data[0]
+#define sTimer   data[1]
+#define sFldEff  data[7]
+
 u32 FldEff_SandFootprints(void)
 {
     u8 spriteId;
-    struct Sprite *sprite;
 
     SetSpritePosToOffsetMapCoords((s16 *)&gFieldEffectArguments[0], (s16 *)&gFieldEffectArguments[1], 8, 8);
     spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_SAND_FOOTPRINTS], gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = gFieldEffectArguments[3];
-        sprite->data[7] = FLDEFF_SAND_FOOTPRINTS;
+        sprite->sFldEff = FLDEFF_SAND_FOOTPRINTS;
         StartSpriteAnim(sprite, gFieldEffectArguments[4]);
     }
     return 0;
@@ -582,16 +571,15 @@ u32 FldEff_SandFootprints(void)
 u32 FldEff_DeepSandFootprints(void)
 {
     u8 spriteId;
-    struct Sprite *sprite;
 
     SetSpritePosToOffsetMapCoords((s16 *)&gFieldEffectArguments[0], (s16 *)&gFieldEffectArguments[1], 8, 8);
     spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_DEEP_SAND_FOOTPRINTS], gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = gFieldEffectArguments[3];
-        sprite->data[7] = FLDEFF_DEEP_SAND_FOOTPRINTS;
+        sprite->sFldEff = FLDEFF_DEEP_SAND_FOOTPRINTS;
         StartSpriteAnim(sprite, gFieldEffectArguments[4]);
     }
     return spriteId;
@@ -600,16 +588,15 @@ u32 FldEff_DeepSandFootprints(void)
 u32 FldEff_BikeTireTracks(void)
 {
     u8 spriteId;
-    struct Sprite *sprite;
 
     SetSpritePosToOffsetMapCoords((s16 *)&gFieldEffectArguments[0], (s16 *)&gFieldEffectArguments[1], 8, 8);
     spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_BIKE_TIRE_TRACKS], gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = gFieldEffectArguments[3];
-        sprite->data[7] = FLDEFF_BIKE_TIRE_TRACKS;
+        sprite->sFldEff = FLDEFF_BIKE_TIRE_TRACKS;
         StartSpriteAnim(sprite, gFieldEffectArguments[4]);
     }
     return spriteId;
@@ -622,14 +609,14 @@ void (*const gFadeFootprintsTireTracksFuncs[])(struct Sprite *) = {
 
 void UpdateFootprintsTireTracksFieldEffect(struct Sprite *sprite)
 {
-    gFadeFootprintsTireTracksFuncs[sprite->data[0]](sprite);
+    gFadeFootprintsTireTracksFuncs[sprite->sState](sprite);
 }
 
 static void FadeFootprintsTireTracks_Step0(struct Sprite *sprite)
 {
     // Wait 40 frames before the flickering starts.
-    if (++sprite->data[1] > 40)
-        sprite->data[0] = 1;
+    if (++sprite->sTimer > 40)
+        sprite->sState = 1;
 
     UpdateObjectEventSpriteInvisibility(sprite, FALSE);
 }
@@ -637,36 +624,37 @@ static void FadeFootprintsTireTracks_Step0(struct Sprite *sprite)
 static void FadeFootprintsTireTracks_Step1(struct Sprite *sprite)
 {
     sprite->invisible ^= 1;
-    sprite->data[1]++;
+    sprite->sTimer++;
     UpdateObjectEventSpriteInvisibility(sprite, sprite->invisible);
-    if (sprite->data[1] > 56)
-    {
-        FieldEffectStop(sprite, sprite->data[7]);
-    }
+    if (sprite->sTimer > 56)
+        FieldEffectStop(sprite, sprite->sFldEff);
 }
 
+#undef sState
+#undef sTimer
+#undef sFldEff
+
+// Sprite data for FLDEFF_SPLASH
+#define sLocalId  data[0]
+#define sMapNum   data[1]
+#define sMapGroup data[2]
+
 u32 FldEff_Splash(void)
 {
-    u8 objectEventId;
-    struct ObjectEvent *objectEvent;
-    u8 spriteId;
-    struct Sprite *sprite;
-    const struct ObjectEventGraphicsInfo *graphicsInfo;
-    struct Sprite *linkedSprite;
-
-    objectEventId = GetObjectEventIdByLocalIdAndMap(gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
-    objectEvent = &gObjectEvents[objectEventId];
-    spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_SPLASH], 0, 0, 0);
+    u8 objectEventId = GetObjectEventIdByLocalIdAndMap(gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
+    struct ObjectEvent *objectEvent = &gObjectEvents[objectEventId];
+    u8 spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_SPLASH], 0, 0, 0);
     if (spriteId != MAX_SPRITES)
     {
-        graphicsInfo = GetObjectEventGraphicsInfo(objectEvent->graphicsId);
-        sprite = &gSprites[spriteId];
+        struct Sprite *linkedSprite;
+        const struct ObjectEventGraphicsInfo *graphicsInfo = GetObjectEventGraphicsInfo(objectEvent->graphicsId);
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         linkedSprite = &gSprites[objectEvent->spriteId];
         sprite->oam.priority = linkedSprite->oam.priority;
-        sprite->data[0] = gFieldEffectArguments[0];
-        sprite->data[1] = gFieldEffectArguments[1];
-        sprite->data[2] = gFieldEffectArguments[2];
+        sprite->sLocalId = gFieldEffectArguments[0];
+        sprite->sMapNum = gFieldEffectArguments[1];
+        sprite->sMapGroup = gFieldEffectArguments[2];
         sprite->y2 = (graphicsInfo->height >> 1) - 4;
         PlaySE(SE_PUDDLE);
     }
@@ -677,7 +665,7 @@ void UpdateSplashFieldEffect(struct Sprite *sprite)
 {
     u8 objectEventId;
 
-    if (sprite->animEnded || TryGetObjectEventIdByLocalIdAndMap(sprite->data[0], sprite->data[1], sprite->data[2], &objectEventId))
+    if (sprite->animEnded || TryGetObjectEventIdByLocalIdAndMap(sprite->sLocalId, sprite->sMapNum, sprite->sMapGroup, &objectEventId))
     {
         FieldEffectStop(sprite, FLDEFF_SPLASH);
     }
@@ -689,20 +677,23 @@ void UpdateSplashFieldEffect(struct Sprite *sprite)
     }
 }
 
+#undef sLocalId
+#undef sMapNum
+#undef sMapGroup
+
 u32 FldEff_JumpSmallSplash(void)
 {
     u8 spriteId;
-    struct Sprite *sprite;
 
     SetSpritePosToOffsetMapCoords((s16 *)&gFieldEffectArguments[0], (s16 *)&gFieldEffectArguments[1], 8, 12);
     spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_JUMP_SMALL_SPLASH], gFieldEffectArguments[0], gFieldEffectArguments[1], 0);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = gFieldEffectArguments[3];
-        sprite->data[0] = gFieldEffectArguments[2];
-        sprite->data[1] = FLDEFF_JUMP_SMALL_SPLASH;
+        sprite->sJumpElevation = gFieldEffectArguments[2];
+        sprite->sJumpFldEff = FLDEFF_JUMP_SMALL_SPLASH;
     }
     return 0;
 }
@@ -710,44 +701,44 @@ u32 FldEff_JumpSmallSplash(void)
 u32 FldEff_JumpBigSplash(void)
 {
     u8 spriteId;
-    struct Sprite *sprite;
 
     SetSpritePosToOffsetMapCoords((s16 *)&gFieldEffectArguments[0], (s16 *)&gFieldEffectArguments[1], 8, 8);
     spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_JUMP_BIG_SPLASH], gFieldEffectArguments[0], gFieldEffectArguments[1], 0);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = gFieldEffectArguments[3];
-        sprite->data[0] = gFieldEffectArguments[2];
-        sprite->data[1] = FLDEFF_JUMP_BIG_SPLASH;
+        sprite->sJumpElevation = gFieldEffectArguments[2];
+        sprite->sJumpFldEff = FLDEFF_JUMP_BIG_SPLASH;
     }
     return 0;
 }
 
+// Sprite data for FLDEFF_FEET_IN_FLOWING_WATER
+#define sLocalId  data[0]
+#define sMapNum   data[1]
+#define sMapGroup data[2]
+#define sPrevX    data[3]
+#define sPrevY    data[4]
+
 u32 FldEff_FeetInFlowingWater(void)
 {
-    u8 objectEventId;
-    struct ObjectEvent *objectEvent;
-    u8 spriteId;
-    struct Sprite *sprite;
-    const struct ObjectEventGraphicsInfo *graphicsInfo;
-
-    objectEventId = GetObjectEventIdByLocalIdAndMap(gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
-    objectEvent = &gObjectEvents[objectEventId];
-    spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_SPLASH], 0, 0, 0);
+    u8 objectEventId = GetObjectEventIdByLocalIdAndMap(gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
+    struct ObjectEvent *objectEvent = &gObjectEvents[objectEventId];
+    u8 spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_SPLASH], 0, 0, 0);
     if (spriteId != MAX_SPRITES)
     {
-        graphicsInfo = GetObjectEventGraphicsInfo(objectEvent->graphicsId);
-        sprite = &gSprites[spriteId];
+        const struct ObjectEventGraphicsInfo *graphicsInfo = GetObjectEventGraphicsInfo(objectEvent->graphicsId);
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->callback = UpdateFeetInFlowingWaterFieldEffect;
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = gSprites[objectEvent->spriteId].oam.priority;
-        sprite->data[0] = gFieldEffectArguments[0];
-        sprite->data[1] = gFieldEffectArguments[1];
-        sprite->data[2] = gFieldEffectArguments[2];
-        sprite->data[3] = -1;
-        sprite->data[4] = -1;
+        sprite->sLocalId = gFieldEffectArguments[0];
+        sprite->sMapNum = gFieldEffectArguments[1];
+        sprite->sMapGroup = gFieldEffectArguments[2];
+        sprite->sPrevX = -1;
+        sprite->sPrevY = -1;
         sprite->y2 = (graphicsInfo->height >> 1) - 4;
         StartSpriteAnim(sprite, 1);
     }
@@ -757,69 +748,70 @@ u32 FldEff_FeetInFlowingWater(void)
 static void UpdateFeetInFlowingWaterFieldEffect(struct Sprite *sprite)
 {
     u8 objectEventId;
-    struct Sprite *linkedSprite;
-    struct ObjectEvent *objectEvent;
 
-    if (TryGetObjectEventIdByLocalIdAndMap(sprite->data[0], sprite->data[1], sprite->data[2], &objectEventId) || !gObjectEvents[objectEventId].inShallowFlowingWater)
+    if (TryGetObjectEventIdByLocalIdAndMap(sprite->sLocalId, sprite->sMapNum, sprite->sMapGroup, &objectEventId) || !gObjectEvents[objectEventId].inShallowFlowingWater)
     {
         FieldEffectStop(sprite, FLDEFF_FEET_IN_FLOWING_WATER);
     }
     else
     {
-        objectEvent = &gObjectEvents[objectEventId];
-        linkedSprite = &gSprites[objectEvent->spriteId];
+        struct ObjectEvent *objectEvent = &gObjectEvents[objectEventId];
+        struct Sprite *linkedSprite = &gSprites[objectEvent->spriteId];
         sprite->x = linkedSprite->x;
         sprite->y = linkedSprite->y;
         sprite->subpriority = linkedSprite->subpriority;
         UpdateObjectEventSpriteInvisibility(sprite, FALSE);
-        if (objectEvent->currentCoords.x != sprite->data[3] || objectEvent->currentCoords.y != sprite->data[4])
+        if (objectEvent->currentCoords.x != sprite->sPrevX || objectEvent->currentCoords.y != sprite->sPrevY)
         {
-            sprite->data[3] = objectEvent->currentCoords.x;
-            sprite->data[4] = objectEvent->currentCoords.y;
+            sprite->sPrevX = objectEvent->currentCoords.x;
+            sprite->sPrevY = objectEvent->currentCoords.y;
             if (!sprite->invisible)
-            {
                 PlaySE(SE_PUDDLE);
-            }
         }
     }
 }
 
+#undef sLocalId
+#undef sMapNum
+#undef sMapGroup
+#undef sPrevX
+#undef sPrevY
+
 u32 FldEff_Ripple(void)
 {
-    u8 spriteId;
-    struct Sprite *sprite;
-
-    spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_RIPPLE], gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
+    u8 spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_RIPPLE], gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = gFieldEffectArguments[3];
-        sprite->data[0] = FLDEFF_RIPPLE;
+        sprite->sWaitFldEff = FLDEFF_RIPPLE;
     }
     return 0;
 }
 
+// Sprite data for FLDEFF_HOT_SPRINGS_WATER
+#define sLocalId  data[0]
+#define sMapNum   data[1]
+#define sMapGroup data[2]
+#define sPrevX    data[3]
+#define sPrevY    data[4]
+
 u32 FldEff_HotSpringsWater(void)
 {
-    u8 objectEventId;
-    struct ObjectEvent *objectEvent;
-    u8 spriteId;
-    struct Sprite *sprite;
-
-    objectEventId = GetObjectEventIdByLocalIdAndMap(gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
-    objectEvent = &gObjectEvents[objectEventId];
-    spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_HOT_SPRINGS_WATER], 0, 0, 0);
+    u8 objectEventId = GetObjectEventIdByLocalIdAndMap(gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
+    struct ObjectEvent *objectEvent = &gObjectEvents[objectEventId];
+    u8 spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_HOT_SPRINGS_WATER], 0, 0, 0);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = gSprites[objectEvent->spriteId].oam.priority;
-        sprite->data[0] = gFieldEffectArguments[0];
-        sprite->data[1] = gFieldEffectArguments[1];
-        sprite->data[2] = gFieldEffectArguments[2];
-        sprite->data[3] = gSprites[objectEvent->spriteId].x;
-        sprite->data[4] = gSprites[objectEvent->spriteId].y;
+        sprite->sLocalId = gFieldEffectArguments[0];
+        sprite->sMapNum = gFieldEffectArguments[1];
+        sprite->sMapGroup = gFieldEffectArguments[2];
+        sprite->sPrevX = gSprites[objectEvent->spriteId].x; // Unused
+        sprite->sPrevY = gSprites[objectEvent->spriteId].y; // Unused
     }
     return 0;
 }
@@ -827,17 +819,15 @@ u32 FldEff_HotSpringsWater(void)
 void UpdateHotSpringsWaterFieldEffect(struct Sprite *sprite)
 {
     u8 objectEventId;
-    const struct ObjectEventGraphicsInfo *graphicsInfo;
-    struct Sprite *linkedSprite;
 
-    if (TryGetObjectEventIdByLocalIdAndMap(sprite->data[0], sprite->data[1], sprite->data[2], &objectEventId) || !gObjectEvents[objectEventId].inHotSprings)
+    if (TryGetObjectEventIdByLocalIdAndMap(sprite->sLocalId, sprite->sMapNum, sprite->sMapGroup, &objectEventId) || !gObjectEvents[objectEventId].inHotSprings)
     {
         FieldEffectStop(sprite, FLDEFF_HOT_SPRINGS_WATER);
     }
     else
     {
-        graphicsInfo = GetObjectEventGraphicsInfo(gObjectEvents[objectEventId].graphicsId);
-        linkedSprite = &gSprites[gObjectEvents[objectEventId].spriteId];
+        const struct ObjectEventGraphicsInfo *graphicsInfo = GetObjectEventGraphicsInfo(gObjectEvents[objectEventId].graphicsId);
+        struct Sprite *linkedSprite = &gSprites[gObjectEvents[objectEventId].spriteId];
         sprite->x = linkedSprite->x;
         sprite->y = (graphicsInfo->height >> 1) + linkedSprite->y - 8;
         sprite->subpriority = linkedSprite->subpriority - 1;
@@ -845,19 +835,24 @@ void UpdateHotSpringsWaterFieldEffect(struct Sprite *sprite)
     }
 }
 
+#undef sLocalId
+#undef sMapNum
+#undef sMapGroup
+#undef sPrevX
+#undef sPrevY
+
 u32 FldEff_UnusedGrass(void)
 {
     u8 spriteId;
-    struct Sprite *sprite;
 
     SetSpritePosToOffsetMapCoords((s16 *)&gFieldEffectArguments[0], (s16 *)&gFieldEffectArguments[1], 8, 8);
     spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_UNUSED_GRASS], gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = gFieldEffectArguments[3];
-        sprite->data[0] = FLDEFF_UNUSED_GRASS;
+        sprite->sWaitFldEff = FLDEFF_UNUSED_GRASS;
     }
     return 0;
 }
@@ -865,16 +860,15 @@ u32 FldEff_UnusedGrass(void)
 u32 FldEff_UnusedGrass2(void)
 {
     u8 spriteId;
-    struct Sprite *sprite;
 
     SetSpritePosToOffsetMapCoords((s16 *)&gFieldEffectArguments[0], (s16 *)&gFieldEffectArguments[1], 8, 8);
     spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_UNUSED_GRASS_2], gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = gFieldEffectArguments[3];
-        sprite->data[0] = FLDEFF_UNUSED_GRASS_2;
+        sprite->sWaitFldEff = FLDEFF_UNUSED_GRASS_2;
     }
     return 0;
 }
@@ -882,16 +876,15 @@ u32 FldEff_UnusedGrass2(void)
 u32 FldEff_UnusedSand(void)
 {
     u8 spriteId;
-    struct Sprite *sprite;
 
     SetSpritePosToOffsetMapCoords((s16 *)&gFieldEffectArguments[0], (s16 *)&gFieldEffectArguments[1], 8, 8);
     spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_UNUSED_SAND], gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = gFieldEffectArguments[3];
-        sprite->data[0] = FLDEFF_UNUSED_SAND;
+        sprite->sWaitFldEff = FLDEFF_UNUSED_SAND;
     }
     return 0;
 }
@@ -899,16 +892,15 @@ u32 FldEff_UnusedSand(void)
 u32 FldEff_WaterSurfacing(void)
 {
     u8 spriteId;
-    struct Sprite *sprite;
 
     SetSpritePosToOffsetMapCoords((s16 *)&gFieldEffectArguments[0], (s16 *)&gFieldEffectArguments[1], 8, 8);
     spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_WATER_SURFACING], gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = gFieldEffectArguments[3];
-        sprite->data[0] = FLDEFF_WATER_SURFACING;
+        sprite->sWaitFldEff = FLDEFF_WATER_SURFACING;
     }
     return 0;
 }
@@ -933,18 +925,15 @@ void StartAshFieldEffect(s16 x, s16 y, u16 metatileId, s16 delay)
 
 u32 FldEff_Ash(void)
 {
-    s16 x;
-    s16 y;
     u8 spriteId;
-    struct Sprite *sprite;
 
-    x = gFieldEffectArguments[0];
-    y = gFieldEffectArguments[1];
+    s16 x = gFieldEffectArguments[0];
+    s16 y = gFieldEffectArguments[1];
     SetSpritePosToOffsetMapCoords(&x, &y, 8, 8);
     spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_ASH], x, y, gFieldEffectArguments[2]);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = gFieldEffectArguments[3];
         sprite->sX = gFieldEffectArguments[0];
@@ -998,27 +987,30 @@ static void UpdateAshFieldEffect_End(struct Sprite *sprite)
 #undef sDelay
 
 // Sprite data for FLDEFF_SURF_BLOB
-#define tBitfield data[0]
-#define tPlayerOffset data[1]
-#define tPlayerObjId data[2]
-
+#define sBitfield     data[0]
+#define sPlayerOffset data[1]
+#define sPlayerObjId  data[2]
+#define sVelocity     data[3]
+#define sTimer        data[4]
+#define sIntervalIdx  data[5]
+#define sPrevX        data[6]
+#define sPrevY        data[7]
 
 u32 FldEff_SurfBlob(void)
 {
     u8 spriteId;
-    struct Sprite *sprite;
 
     SetSpritePosToOffsetMapCoords((s16 *)&gFieldEffectArguments[0], (s16 *)&gFieldEffectArguments[1], 8, 8);
-    spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_SURF_BLOB], gFieldEffectArguments[0], gFieldEffectArguments[1], 0x96);
+    spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_SURF_BLOB], gFieldEffectArguments[0], gFieldEffectArguments[1], 150);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.paletteNum = 0;
-        sprite->tPlayerObjId = gFieldEffectArguments[2];
-        sprite->data[3] = -1;
-        sprite->data[6] = -1;
-        sprite->data[7] = -1;
+        sprite->sPlayerObjId = gFieldEffectArguments[2];
+        sprite->sVelocity = -1;
+        sprite->sPrevX = -1;
+        sprite->sPrevY = -1;
     }
     FieldEffectActiveListRemove(FLDEFF_SURF_BLOB);
     return spriteId;
@@ -1027,43 +1019,40 @@ u32 FldEff_SurfBlob(void)
 
 void SetSurfBlob_BobState(u8 spriteId, u8 state)
 {
-    gSprites[spriteId].data[0] = (gSprites[spriteId].data[0] & ~0xF) | (state & 0xF);
+    gSprites[spriteId].sBitfield = (gSprites[spriteId].sBitfield & ~0xF) | (state & 0xF);
 }
 
 void SetSurfBlob_DontSyncAnim(u8 spriteId, bool8 dontSync)
 {
-    gSprites[spriteId].data[0] = (gSprites[spriteId].data[0] & ~0xF0) | ((dontSync & 0xF) << 4);
+    gSprites[spriteId].sBitfield = (gSprites[spriteId].sBitfield & ~0xF0) | ((dontSync & 0xF) << 4);
 }
 
 void SetSurfBlob_PlayerOffset(u8 spriteId, bool8 hasOffset, s16 offset)
 {
-    gSprites[spriteId].data[0] = (gSprites[spriteId].data[0] & ~0xF00) | ((hasOffset & 0xF) << 8);
-    gSprites[spriteId].tPlayerOffset = offset;
+    gSprites[spriteId].sBitfield = (gSprites[spriteId].sBitfield & ~0xF00) | ((hasOffset & 0xF) << 8);
+    gSprites[spriteId].sPlayerOffset = offset;
 }
 
 static u8 GetSurfBlob_BobState(struct Sprite *sprite)
 {
-    return sprite->data[0] & 0xF;
+    return sprite->sBitfield & 0xF;
 }
 
 // Never TRUE
 static u8 GetSurfBlob_DontSyncAnim(struct Sprite *sprite)
 {
-    return (sprite->data[0] & 0xF0) >> 4;
+    return (sprite->sBitfield & 0xF0) >> 4;
 }
 
 static u8 GetSurfBlob_HasPlayerOffset(struct Sprite *sprite)
 {
-    return (sprite->data[0] & 0xF00) >> 8;
+    return (sprite->sBitfield & 0xF00) >> 8;
 }
 
 void UpdateSurfBlobFieldEffect(struct Sprite *sprite)
 {
-    struct ObjectEvent *playerObj;
-    struct Sprite *playerSprite;
-
-    playerObj = &gObjectEvents[sprite->tPlayerObjId];
-    playerSprite = &gSprites[playerObj->spriteId];
+    struct ObjectEvent *playerObj = &gObjectEvents[sprite->sPlayerObjId];
+    struct Sprite *playerSprite = &gSprites[playerObj->spriteId];
     SynchroniseSurfAnim(playerObj, sprite);
     SynchroniseSurfPosition(playerObj, sprite);
     UpdateBobbingEffect(playerObj, playerSprite, sprite);
@@ -1096,17 +1085,19 @@ void SynchroniseSurfPosition(struct ObjectEvent *playerObj, struct Sprite *sprit
     s16 y = playerObj->currentCoords.y;
     s32 spriteY = sprite->y2;
 
-    if (spriteY == 0 && (x != sprite->data[6] || y != sprite->data[7]))
+    if (spriteY == 0 && (x != sprite->sPrevX || y != sprite->sPrevY))
     {
-        sprite->data[5] = spriteY;
-        sprite->data[6] = x;
-        sprite->data[7] = y;
-        for (i = DIR_SOUTH; i <= DIR_EAST; i++, x = sprite->data[6], y = sprite->data[7])
+        // Player is moving while surfing, update position.
+        sprite->sIntervalIdx = 0;
+        sprite->sPrevX = x;
+        sprite->sPrevY = y;
+        for (i = DIR_SOUTH; i <= DIR_EAST; i++, x = sprite->sPrevX, y = sprite->sPrevY)
         {
             MoveCoords(i, &x, &y);
             if (MapGridGetElevationAt(x, y) == 3)
             {
-                sprite->data[5]++;
+                // While dismounting the surf blob bobs at a slower rate
+                sprite->sIntervalIdx++;
                 break;
             }
         }
@@ -1115,46 +1106,54 @@ void SynchroniseSurfPosition(struct ObjectEvent *playerObj, struct Sprite *sprit
 
 static void UpdateBobbingEffect(struct ObjectEvent *playerObj, struct Sprite *playerSprite, struct Sprite *sprite)
 {
-    u16 intervals[] = {3, 7};
+    // The frame interval at which to update the blob's y movement.
+    // Normally every 4th frame, but every 8th frame while dismounting.
+    u16 intervals[] = {0x3, 0x7};
+
     u8 bobState = GetSurfBlob_BobState(sprite);
     if (bobState != BOB_NONE)
     {
-        // Update bobbing position of surf blob
-        if (((u16)(++sprite->data[4]) & intervals[sprite->data[5]]) == 0)
-        {
-            sprite->y2 += sprite->data[3];
-        }
-        if ((sprite->data[4] & 15) == 0)
-        {
-            sprite->data[3] = -sprite->data[3];
-        }
+        // Update vertical position of surf blob
+        if (((u16)(++sprite->sTimer) & intervals[sprite->sIntervalIdx]) == 0)
+            sprite->y2 += sprite->sVelocity;
+
+        // Reverse bob direction
+        if ((sprite->sTimer & 15) == 0)
+            sprite->sVelocity = -sprite->sVelocity;
+
         if (bobState != BOB_JUST_MON)
         {
-            // Update bobbing position of player
+            // Update vertical position of player
             if (!GetSurfBlob_HasPlayerOffset(sprite))
                 playerSprite->y2 = sprite->y2;
             else
-                playerSprite->y2 = sprite->tPlayerOffset + sprite->y2;
+                playerSprite->y2 = sprite->sPlayerOffset + sprite->y2;
             sprite->x = playerSprite->x;
             sprite->y = playerSprite->y + 8;
         }
     }
 }
 
+#undef sBitfield
+#undef sPlayerOffset
+#undef sPlayerObjId
+#undef sVelocity
+#undef sTimer
+#undef sIntervalIdx
+#undef sPrevX
+#undef sPrevY
+
 #define sSpriteId data[0]
 #define sBobY     data[1]
 #define sTimer    data[2]
 
 u8 StartUnderwaterSurfBlobBobbing(u8 blobSpriteId)
 {
-    u8 spriteId;
-    struct Sprite *sprite;
-
     // Create a dummy sprite with its own callback
     // that tracks the actual surf blob sprite and
     // makes it bob up and down underwater
-    spriteId = CreateSpriteAtEnd(&gDummySpriteTemplate, 0, 0, -1);
-    sprite = &gSprites[spriteId];
+    u8 spriteId = CreateSpriteAtEnd(&gDummySpriteTemplate, 0, 0, -1);
+    struct Sprite *sprite = &gSprites[spriteId];
     sprite->callback = SpriteCB_UnderwaterSurfBlob;
     sprite->invisible = TRUE;
     sprite->sSpriteId = blobSpriteId;
@@ -1164,17 +1163,14 @@ u8 StartUnderwaterSurfBlobBobbing(u8 blobSpriteId)
 
 static void SpriteCB_UnderwaterSurfBlob(struct Sprite *sprite)
 {
-    struct Sprite *blobSprite;
+    struct Sprite *blobSprite = &gSprites[sprite->sSpriteId];
 
-    blobSprite = &gSprites[sprite->sSpriteId];
+    // Update vertical position of surf blob
     if (((sprite->sTimer++) & 3) == 0)
-    {
         blobSprite->y2 += sprite->sBobY;
-    }
+    // Reverse direction
     if ((sprite->sTimer & 15) == 0)
-    {
         sprite->sBobY = -sprite->sBobY;
-    }
 }
 
 #undef sSpriteId
@@ -1184,43 +1180,43 @@ static void SpriteCB_UnderwaterSurfBlob(struct Sprite *sprite)
 u32 FldEff_Dust(void)
 {
     u8 spriteId;
-    struct Sprite *sprite;
 
     SetSpritePosToOffsetMapCoords((s16 *)&gFieldEffectArguments[0], (s16 *)&gFieldEffectArguments[1], 8, 12);
     spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_GROUND_IMPACT_DUST], gFieldEffectArguments[0], gFieldEffectArguments[1], 0);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = gFieldEffectArguments[3];
-        sprite->data[0] = gFieldEffectArguments[2];
-        sprite->data[1] = FLDEFF_DUST;
+        sprite->sJumpElevation = gFieldEffectArguments[2];
+        sprite->sJumpFldEff = FLDEFF_DUST;
     }
     return 0;
 }
 
+// Sprite data for FLDEFF_SAND_PILE
+#define sLocalId  data[0]
+#define sMapNum   data[1]
+#define sMapGroup data[2]
+#define sPrevX    data[3]
+#define sPrevY    data[4]
+
 u32 FldEff_SandPile(void)
 {
-    u8 objectEventId;
-    struct ObjectEvent *objectEvent;
-    u8 spriteId;
-    struct Sprite *sprite;
-    const struct ObjectEventGraphicsInfo *graphicsInfo;
-
-    objectEventId = GetObjectEventIdByLocalIdAndMap(gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
-    objectEvent = &gObjectEvents[objectEventId];
-    spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_SAND_PILE], 0, 0, 0);
+    u8 objectEventId = GetObjectEventIdByLocalIdAndMap(gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
+    struct ObjectEvent *objectEvent = &gObjectEvents[objectEventId];
+    u8 spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_SAND_PILE], 0, 0, 0);
     if (spriteId != MAX_SPRITES)
     {
-        graphicsInfo = GetObjectEventGraphicsInfo(objectEvent->graphicsId);
-        sprite = &gSprites[spriteId];
+        const struct ObjectEventGraphicsInfo *graphicsInfo = GetObjectEventGraphicsInfo(objectEvent->graphicsId);
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = gSprites[objectEvent->spriteId].oam.priority;
-        sprite->data[0] = gFieldEffectArguments[0];
-        sprite->data[1] = gFieldEffectArguments[1];
-        sprite->data[2] = gFieldEffectArguments[2];
-        sprite->data[3] = gSprites[objectEvent->spriteId].x;
-        sprite->data[4] = gSprites[objectEvent->spriteId].y;
+        sprite->sLocalId = gFieldEffectArguments[0];
+        sprite->sMapNum = gFieldEffectArguments[1];
+        sprite->sMapGroup = gFieldEffectArguments[2];
+        sprite->sPrevX = gSprites[objectEvent->spriteId].x;
+        sprite->sPrevY = gSprites[objectEvent->spriteId].y;
         sprite->y2 = (graphicsInfo->height >> 1) - 2;
         SeekSpriteAnim(sprite, 2);
     }
@@ -1230,81 +1226,85 @@ u32 FldEff_SandPile(void)
 void UpdateSandPileFieldEffect(struct Sprite *sprite)
 {
     u8 objectEventId;
-    s16 x;
-    s16 y;
 
-    if (TryGetObjectEventIdByLocalIdAndMap(sprite->data[0], sprite->data[1], sprite->data[2], &objectEventId) || !gObjectEvents[objectEventId].inSandPile)
+    if (TryGetObjectEventIdByLocalIdAndMap(sprite->sLocalId, sprite->sMapNum, sprite->sMapGroup, &objectEventId) || !gObjectEvents[objectEventId].inSandPile)
     {
         FieldEffectStop(sprite, FLDEFF_SAND_PILE);
     }
     else
     {
-        y = gSprites[gObjectEvents[objectEventId].spriteId].y;
-        x = gSprites[gObjectEvents[objectEventId].spriteId].x;
-        if (x != sprite->data[3] || y != sprite->data[4])
+        s16 parentY = gSprites[gObjectEvents[objectEventId].spriteId].y;
+        s16 parentX = gSprites[gObjectEvents[objectEventId].spriteId].x;
+        if (parentX != sprite->sPrevX || parentY != sprite->sPrevY)
         {
-            sprite->data[3] = x;
-            sprite->data[4] = y;
+            sprite->sPrevX = parentX;
+            sprite->sPrevY = parentY;
             if (sprite->animEnded)
-            {
                 StartSpriteAnim(sprite, 0);
-            }
         }
-        sprite->x = x;
-        sprite->y = y;
+        sprite->x = parentX;
+        sprite->y = parentY;
         sprite->subpriority = gSprites[gObjectEvents[objectEventId].spriteId].subpriority;
         UpdateObjectEventSpriteInvisibility(sprite, FALSE);
     }
 }
 
+#undef sLocalId
+#undef sMapNum
+#undef sMapGroup
+#undef sPrevX
+#undef sPrevY
+
 u32 FldEff_Bubbles(void)
 {
     u8 spriteId;
-    struct Sprite *sprite;
 
     SetSpritePosToOffsetMapCoords((s16 *)&gFieldEffectArguments[0], (s16 *)&gFieldEffectArguments[1], 8, 0);
-    spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_BUBBLES], gFieldEffectArguments[0], gFieldEffectArguments[1], 0x52);
+    spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_BUBBLES], gFieldEffectArguments[0], gFieldEffectArguments[1], 82);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = 1;
     }
     return 0;
 }
 
+#define sY data[0]
+
 void UpdateBubblesFieldEffect(struct Sprite *sprite)
 {
-    sprite->data[0] += 0x80;
-    sprite->data[0] &= 0x100;
-    sprite->y -= sprite->data[0] >> 8;
+    // Move up 1 every other frame.
+    sprite->sY += ((1 << 8) / 2);
+    sprite->sY &= (1 << 8);
+    sprite->y -= sprite->sY >> 8;
     UpdateObjectEventSpriteInvisibility(sprite, FALSE);
     if (sprite->invisible || sprite->animEnded)
-    {
         FieldEffectStop(sprite, FLDEFF_BUBBLES);
-    }
 }
 
+#undef sY
+
 u32 FldEff_BerryTreeGrowthSparkle(void)
 {
     u8 spriteId;
-    struct Sprite *sprite;
 
     SetSpritePosToOffsetMapCoords((s16 *)&gFieldEffectArguments[0], (s16 *)&gFieldEffectArguments[1], 8, 4);
     spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_SPARKLE], gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2]);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled = TRUE;
         sprite->oam.priority = gFieldEffectArguments[3];
         sprite->oam.paletteNum = 5;
-        sprite->data[0] = FLDEFF_BERRY_TREE_GROWTH_SPARKLE;
+        sprite->sWaitFldEff = FLDEFF_BERRY_TREE_GROWTH_SPARKLE;
     }
     return 0;
 }
 
 // Sprite data for FLDEFF_TREE_DISGUISE / FLDEFF_MOUNTAIN_DISGUISE / FLDEFF_SAND_DISGUISE
 #define sState      data[0]
+#define sFldEff     data[1]
 #define sLocalId    data[2]
 #define sMapNum     data[3]
 #define sMapGroup   data[4]
@@ -1328,7 +1328,6 @@ u32 ShowSandDisguiseFieldEffect(void)
 static u32 ShowDisguiseFieldEffect(u8 fldEff, u8 fldEffObj, u8 paletteNum)
 {
     u8 spriteId;
-    struct Sprite *sprite;
 
     if (TryGetObjectEventIdByLocalIdAndMap(gFieldEffectArguments[0], gFieldEffectArguments[1], gFieldEffectArguments[2], &spriteId))
     {
@@ -1338,7 +1337,7 @@ static u32 ShowDisguiseFieldEffect(u8 fldEff, u8 fldEffObj, u8 paletteNum)
     spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[fldEffObj], 0, 0, 0);
     if (spriteId != MAX_SPRITES)
     {
-        sprite = &gSprites[spriteId];
+        struct Sprite *sprite = &gSprites[spriteId];
         sprite->coordOffsetEnabled ++;
         sprite->oam.paletteNum = paletteNum;
         sprite->sFldEff = fldEff;
@@ -1405,6 +1404,7 @@ bool8 UpdateRevealDisguise(struct ObjectEvent *objectEvent)
 }
 
 #undef sState
+#undef sFldEff
 #undef sLocalId
 #undef sMapNum
 #undef sMapGroup
@@ -1421,7 +1421,7 @@ u32 FldEff_Sparkle(void)
     gFieldEffectArguments[0] += MAP_OFFSET;
     gFieldEffectArguments[1] += MAP_OFFSET;
     SetSpritePosToOffsetMapCoords((s16 *)&gFieldEffectArguments[0], (s16 *)&gFieldEffectArguments[1], 8, 8);
-    spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_SMALL_SPARKLE], gFieldEffectArguments[0], gFieldEffectArguments[1], 0x52);
+    spriteId = CreateSpriteAtEnd(gFieldEffectObjectTemplatePointers[FLDEFFOBJ_SMALL_SPARKLE], gFieldEffectArguments[0], gFieldEffectArguments[1], 82);
     if (spriteId != MAX_SPRITES)
     {
         gSprites[spriteId].oam.priority = gFieldEffectArguments[2];
@@ -1449,7 +1449,9 @@ void UpdateSparkleFieldEffect(struct Sprite *sprite)
 #undef sEndTimer
 
 #define sTimer       data[0]
+#define sMoveTimer   data[1]
 #define sState       data[2]
+#define sVelocity    data[3]
 #define sStartY      data[4]
 #define sCounter     data[5]
 #define sAnimCounter data[6]
@@ -1615,41 +1617,44 @@ void UpdateRayquazaSpotlightEffect(struct Sprite *sprite)
 
     if (sprite->sState == 1)
     {
-        if ((sprite->data[1] & 7) == 0)
-            sprite->y2 += sprite->data[3];
-        if ((sprite->data[1] & 15) == 0)
-            sprite->data[3] = -sprite->data[3];
-        sprite->data[1]++;
+        // Update movement
+        if ((sprite->sMoveTimer & 7) == 0)
+            sprite->y2 += sprite->sVelocity;
+        // Reverse direction
+        if ((sprite->sMoveTimer & 15) == 0)
+            sprite->sVelocity = -sprite->sVelocity;
+        sprite->sMoveTimer++;
     }
 
     sprite->sTimer++;
 }
 
 #undef sTimer
+#undef sMoveTimer
 #undef sState
 #undef sStartY
+#undef sVelocity
 #undef sCounter
 #undef sAnimCounter
 #undef sAnimState
 
-// Used by FLDEFF_JUMP_TALL_GRASS and FLDEFF_JUMP_LONG_GRASS
 void UpdateJumpImpactEffect(struct Sprite *sprite)
 {
     if (sprite->animEnded)
     {
-        FieldEffectStop(sprite, sprite->sFldEff);
+        FieldEffectStop(sprite, sprite->sJumpFldEff);
     }
     else
     {
         UpdateObjectEventSpriteInvisibility(sprite, FALSE);
-        SetObjectSubpriorityByElevation(sprite->sElevation, sprite, 0);
+        SetObjectSubpriorityByElevation(sprite->sJumpElevation, sprite, 0);
     }
 }
 
 void WaitFieldEffectSpriteAnim(struct Sprite *sprite)
 {
     if (sprite->animEnded)
-        FieldEffectStop(sprite, sprite->data[0]);
+        FieldEffectStop(sprite, sprite->sWaitFldEff);
     else
         UpdateObjectEventSpriteInvisibility(sprite, FALSE);
 }
@@ -1658,8 +1663,6 @@ static void UpdateGrassFieldEffectSubpriority(struct Sprite *sprite, u8 elevatio
 {
     u8 i;
     s16 var, xhi, lyhi, yhi, ylo;
-    const struct ObjectEventGraphicsInfo UNUSED *graphicsInfo;
-    struct Sprite *linkedSprite;
 
     SetObjectSubpriorityByElevation(elevation, sprite, subpriority);
     for (i = 0; i < OBJECT_EVENTS_COUNT; i ++)
@@ -1667,8 +1670,9 @@ static void UpdateGrassFieldEffectSubpriority(struct Sprite *sprite, u8 elevatio
         struct ObjectEvent *objectEvent = &gObjectEvents[i];
         if (objectEvent->active)
         {
-            graphicsInfo = GetObjectEventGraphicsInfo(objectEvent->graphicsId);
-            linkedSprite = &gSprites[objectEvent->spriteId];
+            const struct ObjectEventGraphicsInfo UNUSED *graphicsInfo = GetObjectEventGraphicsInfo(objectEvent->graphicsId);
+            struct Sprite *linkedSprite = &gSprites[objectEvent->spriteId];
+
             xhi = sprite->x + sprite->centerToCornerVecX;
             var = sprite->x - sprite->centerToCornerVecX;
             if (xhi < linkedSprite->x && var > linkedSprite->x)
diff --git a/src/map_name_popup.c b/src/map_name_popup.c
index 9c9c85cf595e..75e70dafc136 100644
--- a/src/map_name_popup.c
+++ b/src/map_name_popup.c
@@ -205,22 +205,45 @@ static bool8 UNUSED StartMenu_ShowMapNamePopup(void)
     return TRUE;
 }
 
+// States and data defines for Task_MapNamePopUpWindow
+enum {
+    STATE_SLIDE_IN,
+    STATE_WAIT,
+    STATE_SLIDE_OUT,
+    STATE_UNUSED,
+    STATE_ERASE,
+    STATE_END,
+    STATE_PRINT, // For some reason the first state is numerically last.
+};
+
+#define POPUP_OFFSCREEN_Y  40
+#define POPUP_SLIDE_SPEED  2
+
+#define tState         data[0]
+#define tOnscreenTimer data[1]
+#define tYOffset       data[2]
+#define tIncomingPopUp data[3]
+#define tPrintTimer    data[4]
+
 void ShowMapNamePopup(void)
 {
     if (FlagGet(FLAG_HIDE_MAP_NAME_POPUP) != TRUE)
     {
         if (!FuncIsActiveTask(Task_MapNamePopUpWindow))
         {
+            // New pop up window
             sPopupTaskId = CreateTask(Task_MapNamePopUpWindow, 90);
-            SetGpuReg(REG_OFFSET_BG0VOFS, 40);
-            gTasks[sPopupTaskId].data[0] = 6;
-            gTasks[sPopupTaskId].data[2] = 40;
+            SetGpuReg(REG_OFFSET_BG0VOFS, POPUP_OFFSCREEN_Y);
+            gTasks[sPopupTaskId].tState = STATE_PRINT;
+            gTasks[sPopupTaskId].tYOffset = POPUP_OFFSCREEN_Y;
         }
         else
         {
-            if (gTasks[sPopupTaskId].data[0] != 2)
-                gTasks[sPopupTaskId].data[0] = 2;
-            gTasks[sPopupTaskId].data[3] = 1;
+            // There's already a pop up window running.
+            // Hurry the old pop up offscreen so the new one can appear.
+            if (gTasks[sPopupTaskId].tState != STATE_SLIDE_OUT)
+                gTasks[sPopupTaskId].tState = STATE_SLIDE_OUT;
+            gTasks[sPopupTaskId].tIncomingPopUp = TRUE;
         }
     }
 }
@@ -229,61 +252,65 @@ static void Task_MapNamePopUpWindow(u8 taskId)
 {
     struct Task *task = &gTasks[taskId];
 
-    switch (task->data[0])
+    switch (task->tState)
     {
-    case 6:
-        task->data[4]++;
-        if (task->data[4] > 30)
+    case STATE_PRINT:
+        // Wait, then create and print the pop up window
+        if (++task->tPrintTimer > 30)
         {
-            task->data[0] = 0;
-            task->data[4] = 0;
+            task->tState = STATE_SLIDE_IN;
+            task->tPrintTimer = 0;
             ShowMapNamePopUpWindow();
         }
         break;
-    case 0:
-        task->data[2] -= 2;
-        if (task->data[2] <= 0 )
+    case STATE_SLIDE_IN:
+        // Slide the window onscreen.
+        task->tYOffset -= POPUP_SLIDE_SPEED;
+        if (task->tYOffset <= 0 )
         {
-            task->data[2] = 0;
-            task->data[0] = 1;
+            task->tYOffset = 0;
+            task->tState = STATE_WAIT;
             gTasks[sPopupTaskId].data[1] = 0;
         }
         break;
-    case 1:
-        task->data[1]++;
-        if (task->data[1] > 120 )
+    case STATE_WAIT:
+        // Wait while the window is fully onscreen.
+        if (++task->tOnscreenTimer > 120)
         {
-            task->data[1] = 0;
-            task->data[0] = 2;
+            task->tOnscreenTimer = 0;
+            task->tState = STATE_SLIDE_OUT;
         }
         break;
-    case 2:
-        task->data[2] += 2;
-        if (task->data[2] > 39)
+    case STATE_SLIDE_OUT:
+        // Slide the window offscreen.
+        task->tYOffset += POPUP_SLIDE_SPEED;
+        if (task->tYOffset >= POPUP_OFFSCREEN_Y)
         {
-            task->data[2] = 40;
-            if (task->data[3])
+            task->tYOffset = POPUP_OFFSCREEN_Y;
+            if (task->tIncomingPopUp)
             {
-                task->data[0] = 6;
-                task->data[4] = 0;
-                task->data[3] = 0;
+                // A new pop up window is incoming,
+                // return to the first state to show it.
+                task->tState = STATE_PRINT;
+                task->tPrintTimer = 0;
+                task->tIncomingPopUp = FALSE;
             }
             else
             {
-                task->data[0] = 4;
+                task->tState = STATE_ERASE;
                 return;
             }
         }
         break;
-    case 4:
+    case STATE_ERASE:
         ClearStdWindowAndFrame(GetMapNamePopUpWindowId(), TRUE);
-        task->data[0] = 5;
+        task->tState = STATE_END;
         break;
-    case 5:
+    case STATE_END:
         HideMapNamePopUpWindow();
         return;
     }
-    SetGpuReg(REG_OFFSET_BG0VOFS, task->data[2]);
+    SetGpuReg(REG_OFFSET_BG0VOFS, task->tYOffset);
 }
 
 void HideMapNamePopUpWindow(void)
diff --git a/src/menu_specialized.c b/src/menu_specialized.c
index 456845e868dc..df3685ecfde8 100644
--- a/src/menu_specialized.c
+++ b/src/menu_specialized.c
@@ -588,7 +588,7 @@ static void ConditionGraph_CalcRightHalf(struct ConditionGraph *graph)
     // No need for conditional, positions on the Beauty line are always above the Cute line
     ConditionGraph_CalcLine(graph, graph->scanlineRight[0], &graph->curPositions[GRAPH_BEAUTY], &graph->curPositions[GRAPH_CUTE], TRUE, NULL);
 
-    // Calculate Cute -> Tough line (includes left scanline because this crosses the halfway point)
+    // Calculate Cute -> Smart line (includes left scanline because this crosses the halfway point)
     i = (graph->curPositions[GRAPH_CUTE].y <= graph->curPositions[GRAPH_SMART].y);
     ConditionGraph_CalcLine(graph, graph->scanlineRight[0], &graph->curPositions[GRAPH_CUTE], &graph->curPositions[GRAPH_SMART], i, graph->scanlineLeft[0]);
 
diff --git a/src/mini_printf.c b/src/mini_printf.c
index 9fb4ecfac9e5..2a8c6e5cb780 100644
--- a/src/mini_printf.c
+++ b/src/mini_printf.c
@@ -328,7 +328,7 @@ s32 mini_vpprintf(void* buf, const char *fmt, va_list va)
                     break;
                 case 'S' : // preproc encoded string handler
                     ptr = va_arg(va, char*);
-                    len = StringLength(ptr);
+                    len = StringLength((u8*)ptr);
                     if (pad_to > 0)
                     {
                         len = mini_pad(ptr, len, pad_char, pad_to, bf);
diff --git a/src/player_pc.c b/src/player_pc.c
index 07cc2dba7c43..a10cb2ac2be1 100644
--- a/src/player_pc.c
+++ b/src/player_pc.c
@@ -222,7 +222,7 @@ static const struct MenuAction sItemStorage_MenuActions[] =
     [MENU_EXIT]     = { gText_Cancel,       {ItemStorage_Exit} }
 };
 
-static const struct ItemSlot sNewGamePCItems[] =
+static const u16 sNewGamePCItems[][2] =
 {
     { ITEM_POTION, 1 },
     { ITEM_NONE, 0 }
@@ -355,16 +355,20 @@ static const struct WindowTemplate sWindowTemplates_ItemStorage[ITEMPC_WIN_COUNT
 
 static const u8 sSwapArrowTextColors[] = {TEXT_COLOR_WHITE, TEXT_COLOR_LIGHT_GRAY, TEXT_COLOR_DARK_GRAY};
 
-// Macro below is likely a fakematch, equivalent to sNewGamePCItems[i].quantity
-#define GET_QUANTITY(i) ((u16)((u16 *)sNewGamePCItems + 1)[i * 2])
 void NewGameInitPCItems(void)
 {
     u8 i = 0;
     ClearItemSlots(gSaveBlock1Ptr->pcItems, PC_ITEMS_COUNT);
-    for(; sNewGamePCItems[i].itemId != ITEM_NONE && GET_QUANTITY(i) &&
-        AddPCItem(sNewGamePCItems[i].itemId, GET_QUANTITY(i)) == TRUE; i++);
+
+    while (TRUE)
+    {
+        if (sNewGamePCItems[i][0] == ITEM_NONE || sNewGamePCItems[i][1] == 0)
+            break;
+        if (AddPCItem(sNewGamePCItems[i][0], sNewGamePCItems[i][1]) != TRUE)
+            break;
+        i++;
+    }
 }
-#undef GET_QUANTITY
 
 void BedroomPC(void)
 {
diff --git a/src/title_screen.c b/src/title_screen.c
index 87bf0d970ea5..12015b8bd8aa 100644
--- a/src/title_screen.c
+++ b/src/title_screen.c
@@ -23,6 +23,12 @@
 #include "constants/rgb.h"
 #include "constants/songs.h"
 
+enum {
+    TAG_VERSION = 1000,
+    TAG_PRESS_START_COPYRIGHT,
+    TAG_LOGO_SHINE,
+};
+
 #define VERSION_BANNER_RIGHT_TILEOFFSET 64
 #define VERSION_BANNER_LEFT_X 98
 #define VERSION_BANNER_RIGHT_X 162
@@ -158,8 +164,8 @@ static const union AnimCmd *const sVersionBannerRightAnimTable[] =
 
 static const struct SpriteTemplate sVersionBannerLeftSpriteTemplate =
 {
-    .tileTag = 1000,
-    .paletteTag = 1000,
+    .tileTag = TAG_VERSION,
+    .paletteTag = TAG_VERSION,
     .oam = &sVersionBannerLeftOamData,
     .anims = sVersionBannerLeftAnimTable,
     .images = NULL,
@@ -169,8 +175,8 @@ static const struct SpriteTemplate sVersionBannerLeftSpriteTemplate =
 
 static const struct SpriteTemplate sVersionBannerRightSpriteTemplate =
 {
-    .tileTag = 1000,
-    .paletteTag = 1000,
+    .tileTag = TAG_VERSION,
+    .paletteTag = TAG_VERSION,
     .oam = &sVersionBannerRightOamData,
     .anims = sVersionBannerRightAnimTable,
     .images = NULL,
@@ -183,7 +189,7 @@ static const struct CompressedSpriteSheet sSpriteSheet_EmeraldVersion[] =
     {
         .data = gTitleScreenEmeraldVersionGfx,
         .size = 0x1000,
-        .tag = 1000
+        .tag = TAG_VERSION
     },
     {},
 };
@@ -205,75 +211,80 @@ static const struct OamData sOamData_CopyrightBanner =
     .affineParam = 0,
 };
 
-static const union AnimCmd sCopyrightBannerAnim0[] =
+static const union AnimCmd sAnim_PressStart_0[] =
 {
     ANIMCMD_FRAME(1, 4),
     ANIMCMD_END,
 };
-static const union AnimCmd sCopyrightBannerAnim1[] =
+static const union AnimCmd sAnim_PressStart_1[] =
 {
     ANIMCMD_FRAME(5, 4),
     ANIMCMD_END,
 };
-static const union AnimCmd sCopyrightBannerAnim2[] =
+static const union AnimCmd sAnim_PressStart_2[] =
 {
     ANIMCMD_FRAME(9, 4),
     ANIMCMD_END,
 };
-static const union AnimCmd sCopyrightBannerAnim3[] =
+static const union AnimCmd sAnim_PressStart_3[] =
 {
     ANIMCMD_FRAME(13, 4),
     ANIMCMD_END,
 };
-static const union AnimCmd sCopyrightBannerAnim4[] =
+static const union AnimCmd sAnim_PressStart_4[] =
 {
     ANIMCMD_FRAME(17, 4),
     ANIMCMD_END,
 };
-static const union AnimCmd sCopyrightBannerAnim5[] =
+static const union AnimCmd sAnim_Copyright_0[] =
 {
     ANIMCMD_FRAME(21, 4),
     ANIMCMD_END,
 };
-static const union AnimCmd sCopyrightBannerAnim6[] =
+static const union AnimCmd sAnim_Copyright_1[] =
 {
     ANIMCMD_FRAME(25, 4),
     ANIMCMD_END,
 };
-static const union AnimCmd sCopyrightBannerAnim7[] =
+static const union AnimCmd sAnim_Copyright_2[] =
 {
     ANIMCMD_FRAME(29, 4),
     ANIMCMD_END,
 };
-static const union AnimCmd sCopyrightBannerAnim8[] =
+static const union AnimCmd sAnim_Copyright_3[] =
 {
     ANIMCMD_FRAME(33, 4),
     ANIMCMD_END,
 };
-static const union AnimCmd sCopyrightBannerAnim9[] =
+static const union AnimCmd sAnim_Copyright_4[] =
 {
     ANIMCMD_FRAME(37, 4),
     ANIMCMD_END,
 };
 
-static const union AnimCmd *const sStartCopyrightBannerAnimTable[] =
-{
-    sCopyrightBannerAnim0,
-    sCopyrightBannerAnim1,
-    sCopyrightBannerAnim2,
-    sCopyrightBannerAnim3,
-    sCopyrightBannerAnim4,
-    sCopyrightBannerAnim5,
-    sCopyrightBannerAnim6,
-    sCopyrightBannerAnim7,
-    sCopyrightBannerAnim8,
-    sCopyrightBannerAnim9,
+// The "Press Start" and copyright graphics are each 5 32x8 segments long
+#define NUM_PRESS_START_FRAMES 5
+#define NUM_COPYRIGHT_FRAMES 5
+
+static const union AnimCmd *const sStartCopyrightBannerAnimTable[NUM_PRESS_START_FRAMES + NUM_COPYRIGHT_FRAMES] =
+{
+    sAnim_PressStart_0,
+    sAnim_PressStart_1,
+    sAnim_PressStart_2,
+    sAnim_PressStart_3,
+    sAnim_PressStart_4,
+    [NUM_PRESS_START_FRAMES] =
+    sAnim_Copyright_0,
+    sAnim_Copyright_1,
+    sAnim_Copyright_2,
+    sAnim_Copyright_3,
+    sAnim_Copyright_4,
 };
 
 static const struct SpriteTemplate sStartCopyrightBannerSpriteTemplate =
 {
-    .tileTag = 1001,
-    .paletteTag = 1001,
+    .tileTag = TAG_PRESS_START_COPYRIGHT,
+    .paletteTag = TAG_PRESS_START_COPYRIGHT,
     .oam = &sOamData_CopyrightBanner,
     .anims = sStartCopyrightBannerAnimTable,
     .images = NULL,
@@ -286,7 +297,7 @@ static const struct CompressedSpriteSheet sSpriteSheet_PressStart[] =
     {
         .data = gTitleScreenPressStartGfx,
         .size = 0x520,
-        .tag = 1001
+        .tag = TAG_PRESS_START_COPYRIGHT
     },
     {},
 };
@@ -295,7 +306,7 @@ static const struct SpritePalette sSpritePalette_PressStart[] =
 {
     {
         .data = gTitleScreenPressStartPal,
-        .tag = 1001
+        .tag = TAG_PRESS_START_COPYRIGHT
     },
     {},
 };
@@ -330,8 +341,8 @@ static const union AnimCmd *const sPokemonLogoShineAnimTable[] =
 
 static const struct SpriteTemplate sPokemonLogoShineSpriteTemplate =
 {
-    .tileTag = 1002,
-    .paletteTag = 1001,
+    .tileTag = TAG_LOGO_SHINE,
+    .paletteTag = TAG_PRESS_START_COPYRIGHT,
     .oam = &sPokemonLogoShineOamData,
     .anims = sPokemonLogoShineAnimTable,
     .images = NULL,
@@ -344,15 +355,25 @@ static const struct CompressedSpriteSheet sPokemonLogoShineSpriteSheet[] =
     {
         .data = sTitleScreenLogoShineGfx,
         .size = 0x800,
-        .tag = 1002
+        .tag = TAG_LOGO_SHINE
     },
     {},
 };
 
-// code
+// Task data for the main title screen tasks (Task_TitleScreenPhase#)
+#define tCounter    data[0]
+#define tSkipToNext data[1]
+#define tPointless  data[2] // Incremented but never used to do anything.
+#define tBg2Y       data[3]
+#define tBg1Y       data[4]
+
+// Sprite data for sVersionBannerLeftSpriteTemplate / sVersionBannerRightSpriteTemplate
+#define sAlphaBlendIdx data[0]
+#define sParentTaskId  data[1]
+
 static void SpriteCB_VersionBannerLeft(struct Sprite *sprite)
 {
-    if (gTasks[sprite->data[1]].data[1] != 0)
+    if (gTasks[sprite->sParentTaskId].tSkipToNext)
     {
         sprite->oam.objMode = ST_OAM_OBJ_NORMAL;
         sprite->y = VERSION_BANNER_Y_GOAL;
@@ -361,15 +382,15 @@ static void SpriteCB_VersionBannerLeft(struct Sprite *sprite)
     {
         if (sprite->y != VERSION_BANNER_Y_GOAL)
             sprite->y++;
-        if (sprite->data[0] != 0)
-            sprite->data[0]--;
-        SetGpuReg(REG_OFFSET_BLDALPHA, gTitleScreenAlphaBlend[sprite->data[0]]);
+        if (sprite->sAlphaBlendIdx != 0)
+            sprite->sAlphaBlendIdx--;
+        SetGpuReg(REG_OFFSET_BLDALPHA, gTitleScreenAlphaBlend[sprite->sAlphaBlendIdx]);
     }
 }
 
 static void SpriteCB_VersionBannerRight(struct Sprite *sprite)
 {
-    if (gTasks[sprite->data[1]].data[1] != 0)
+    if (gTasks[sprite->sParentTaskId].tSkipToNext)
     {
         sprite->oam.objMode = ST_OAM_OBJ_NORMAL;
         sprite->y = VERSION_BANNER_Y_GOAL;
@@ -381,13 +402,16 @@ static void SpriteCB_VersionBannerRight(struct Sprite *sprite)
     }
 }
 
+// Sprite data for SpriteCB_PressStartCopyrightBanner
+#define sAnimate data[0]
+#define sTimer   data[1]
+
 static void SpriteCB_PressStartCopyrightBanner(struct Sprite *sprite)
 {
-    if (sprite->data[0] == 1)
+    if (sprite->sAnimate == TRUE)
     {
-        sprite->data[1]++;
         // Alternate between hidden and shown every 16th frame
-        if (sprite->data[1] & 16)
+        if (++sprite->sTimer & 16)
             sprite->invisible = FALSE;
         else
             sprite->invisible = TRUE;
@@ -404,11 +428,11 @@ static void CreatePressStartBanner(s16 x, s16 y)
     u8 spriteId;
 
     x -= 64;
-    for (i = 0; i < 5; i++, x += 32)
+    for (i = 0; i < NUM_PRESS_START_FRAMES; i++, x += 32)
     {
         spriteId = CreateSprite(&sStartCopyrightBannerSpriteTemplate, x, y, 0);
         StartSpriteAnim(&gSprites[spriteId], i);
-        gSprites[spriteId].data[0] = 1;
+        gSprites[spriteId].sAnimate = TRUE;
     }
 }
 
@@ -418,93 +442,122 @@ static void CreateCopyrightBanner(s16 x, s16 y)
     u8 spriteId;
 
     x -= 64;
-    for (i = 0; i < 5; i++, x += 32)
+    for (i = 0; i < NUM_COPYRIGHT_FRAMES; i++, x += 32)
     {
         spriteId = CreateSprite(&sStartCopyrightBannerSpriteTemplate, x, y, 0);
-        StartSpriteAnim(&gSprites[spriteId], i + 5);
+        StartSpriteAnim(&gSprites[spriteId], i + NUM_PRESS_START_FRAMES);
     }
 }
 
+#undef sAnimate
+#undef sTimer
+
+// Defines for SpriteCB_PokemonLogoShine
+enum {
+    SHINE_MODE_SINGLE_NO_BG_COLOR,
+    SHINE_MODE_DOUBLE,
+    SHINE_MODE_SINGLE,
+};
+
+#define SHINE_SPEED  4
+
+#define sMode     data[0]
+#define sBgColor  data[1]
+
 static void SpriteCB_PokemonLogoShine(struct Sprite *sprite)
 {
     if (sprite->x < DISPLAY_WIDTH + 32)
     {
-        if (sprite->data[0]) // Flash background
+        // In any mode except SHINE_MODE_SINGLE_NO_BG_COLOR the background
+        // color will change, in addition to the shine sprite moving.
+        if (sprite->sMode != SHINE_MODE_SINGLE_NO_BG_COLOR)
         {
             u16 backgroundColor;
 
             if (sprite->x < DISPLAY_WIDTH / 2)
             {
                 // Brighten background color
-                if (sprite->data[1] < 31)
-                    sprite->data[1]++;
-                if (sprite->data[1] < 31)
-                    sprite->data[1]++;
+                if (sprite->sBgColor < 31)
+                    sprite->sBgColor++;
+                if (sprite->sBgColor < 31)
+                    sprite->sBgColor++;
             }
             else
             {
                 // Darken background color
-                if (sprite->data[1] != 0)
-                    sprite->data[1]--;
-                if (sprite->data[1] != 0)
-                    sprite->data[1]--;
+                if (sprite->sBgColor != 0)
+                    sprite->sBgColor--;
+                if (sprite->sBgColor != 0)
+                    sprite->sBgColor--;
             }
 
-            backgroundColor = _RGB(sprite->data[1], sprite->data[1], sprite->data[1]);
-            if (sprite->x == DISPLAY_WIDTH / 2 + 12
-                || sprite->x == DISPLAY_WIDTH / 2 + 16
-                || sprite->x == DISPLAY_WIDTH / 2 + 20
-                || sprite->x == DISPLAY_WIDTH / 2 + 24)
+            backgroundColor = _RGB(sprite->sBgColor, sprite->sBgColor, sprite->sBgColor);
+
+            // Flash the background green for 4 frames of movement.
+            // Otherwise use the updating color.
+            if (sprite->x == DISPLAY_WIDTH / 2 + (3 * SHINE_SPEED)
+             || sprite->x == DISPLAY_WIDTH / 2 + (4 * SHINE_SPEED)
+             || sprite->x == DISPLAY_WIDTH / 2 + (5 * SHINE_SPEED)
+             || sprite->x == DISPLAY_WIDTH / 2 + (6 * SHINE_SPEED))
                 gPlttBufferFaded[0] = RGB(24, 31, 12);
             else
                 gPlttBufferFaded[0] = backgroundColor;
         }
-        sprite->x += 4;
+
+        sprite->x += SHINE_SPEED;
     }
     else
     {
+        // Sprite has moved fully offscreen
         gPlttBufferFaded[0] = RGB_BLACK;
         DestroySprite(sprite);
     }
 }
 
-static void SpriteCB_PokemonLogoShine2(struct Sprite *sprite)
+static void SpriteCB_PokemonLogoShine_Fast(struct Sprite *sprite)
 {
     if (sprite->x < DISPLAY_WIDTH + 32)
-        sprite->x += 8;
+        sprite->x += SHINE_SPEED * 2;
     else
         DestroySprite(sprite);
 }
 
-static void StartPokemonLogoShine(u8 flashBg)
+static void StartPokemonLogoShine(u8 mode)
 {
     u8 spriteId;
 
-    switch (flashBg)
+    switch (mode)
     {
-    case 0:
-    case 2:
+    case SHINE_MODE_SINGLE_NO_BG_COLOR:
+    case SHINE_MODE_SINGLE:
+        // Create one regular shine sprite.
+        // If mode is SHINE_MODE_SINGLE it will also change the background color.
         spriteId = CreateSprite(&sPokemonLogoShineSpriteTemplate, 0, 68, 0);
         gSprites[spriteId].oam.objMode = ST_OAM_OBJ_WINDOW;
-        gSprites[spriteId].data[0] = flashBg;
+        gSprites[spriteId].sMode = mode;
         break;
-    case 1:
+    case SHINE_MODE_DOUBLE:
+        // Create an invisible sprite with mode set to update the background color
         spriteId = CreateSprite(&sPokemonLogoShineSpriteTemplate, 0, 68, 0);
         gSprites[spriteId].oam.objMode = ST_OAM_OBJ_WINDOW;
-        gSprites[spriteId].data[0] = flashBg;
+        gSprites[spriteId].sMode = mode;
         gSprites[spriteId].invisible = TRUE;
 
+        // Create two faster shine sprites
         spriteId = CreateSprite(&sPokemonLogoShineSpriteTemplate, 0, 68, 0);
-        gSprites[spriteId].callback = SpriteCB_PokemonLogoShine2;
+        gSprites[spriteId].callback = SpriteCB_PokemonLogoShine_Fast;
         gSprites[spriteId].oam.objMode = ST_OAM_OBJ_WINDOW;
 
         spriteId = CreateSprite(&sPokemonLogoShineSpriteTemplate, -80, 68, 0);
-        gSprites[spriteId].callback = SpriteCB_PokemonLogoShine2;
+        gSprites[spriteId].callback = SpriteCB_PokemonLogoShine_Fast;
         gSprites[spriteId].oam.objMode = ST_OAM_OBJ_WINDOW;
         break;
     }
 }
 
+#undef sMode
+#undef sBgColor
+
 static void VBlankCB(void)
 {
     ScanlineEffect_InitHBlankDmaTransfer();
@@ -514,9 +567,6 @@ static void VBlankCB(void)
     SetGpuReg(REG_OFFSET_BG1VOFS, gBattle_BG1_Y);
 }
 
-#define tCounter data[0]
-#define tSkipToNext data[1]
-
 void CB2_InitTitleScreen(void)
 {
     switch (gMain.state)
@@ -573,13 +623,13 @@ void CB2_InitTitleScreen(void)
 
         gTasks[taskId].tCounter = 256;
         gTasks[taskId].tSkipToNext = FALSE;
-        gTasks[taskId].data[2] = -16;
-        gTasks[taskId].data[3] = -32;
+        gTasks[taskId].tPointless = -16;
+        gTasks[taskId].tBg2Y = -32;
         gMain.state = 3;
         break;
     }
     case 3:
-        BeginNormalPaletteFade(PALETTES_ALL, 1, 0x10, 0, RGB_WHITEALPHA);
+        BeginNormalPaletteFade(PALETTES_ALL, 1, 16, 0, RGB_WHITEALPHA);
         SetVBlankCallback(VBlankCB);
         gMain.state = 4;
         break;
@@ -614,7 +664,7 @@ void CB2_InitTitleScreen(void)
     case 5:
         if (!UpdatePaletteFade())
         {
-            StartPokemonLogoShine(0);
+            StartPokemonLogoShine(SHINE_MODE_SINGLE_NO_BG_COLOR);
             ScanlineEffect_InitWave(0, DISPLAY_HEIGHT, 4, 4, 0, SCANLINE_EFFECT_REG_BG1HOFS, TRUE);
             SetMainCallback2(MainCB2);
         }
@@ -634,7 +684,7 @@ static void MainCB2(void)
 static void Task_TitleScreenPhase1(u8 taskId)
 {
     // Skip to next phase when A, B, Start, or Select is pressed
-    if (JOY_NEW(A_B_START_SELECT) || gTasks[taskId].data[1] != 0)
+    if (JOY_NEW(A_B_START_SELECT) || gTasks[taskId].tSkipToNext)
     {
         gTasks[taskId].tSkipToNext = TRUE;
         gTasks[taskId].tCounter = 0;
@@ -644,9 +694,9 @@ static void Task_TitleScreenPhase1(u8 taskId)
     {
         u16 frameNum = gTasks[taskId].tCounter;
         if (frameNum == 176)
-            StartPokemonLogoShine(1);
+            StartPokemonLogoShine(SHINE_MODE_DOUBLE);
         else if (frameNum == 64)
-            StartPokemonLogoShine(2);
+            StartPokemonLogoShine(SHINE_MODE_SINGLE);
 
         gTasks[taskId].tCounter--;
     }
@@ -663,18 +713,21 @@ static void Task_TitleScreenPhase1(u8 taskId)
 
         // Create left side of version banner
         spriteId = CreateSprite(&sVersionBannerLeftSpriteTemplate, VERSION_BANNER_LEFT_X, VERSION_BANNER_Y, 0);
-        gSprites[spriteId].data[0] = 64;
-        gSprites[spriteId].data[1] = taskId;
+        gSprites[spriteId].sAlphaBlendIdx = ARRAY_COUNT(gTitleScreenAlphaBlend);
+        gSprites[spriteId].sParentTaskId = taskId;
 
         // Create right side of version banner
         spriteId = CreateSprite(&sVersionBannerRightSpriteTemplate, VERSION_BANNER_RIGHT_X, VERSION_BANNER_Y, 0);
-        gSprites[spriteId].data[1] = taskId;
+        gSprites[spriteId].sParentTaskId = taskId;
 
         gTasks[taskId].tCounter = 144;
         gTasks[taskId].func = Task_TitleScreenPhase2;
     }
 }
 
+#undef sParentTaskId
+#undef sAlphaBlendIdx
+
 // Create "Press Start" and copyright banners, and slide Pokemon logo up
 static void Task_TitleScreenPhase2(u8 taskId)
 {
@@ -705,31 +758,31 @@ static void Task_TitleScreenPhase2(u8 taskId)
                                     | DISPCNT_OBJ_ON);
         CreatePressStartBanner(START_BANNER_X, 108);
         CreateCopyrightBanner(START_BANNER_X, 148);
-        gTasks[taskId].data[4] = 0;
+        gTasks[taskId].tBg1Y = 0;
         gTasks[taskId].func = Task_TitleScreenPhase3;
     }
 
-    if (!(gTasks[taskId].tCounter & 3) && gTasks[taskId].data[2] != 0)
-        gTasks[taskId].data[2]++;
-    if (!(gTasks[taskId].tCounter & 1) && gTasks[taskId].data[3] != 0)
-        gTasks[taskId].data[3]++;
+    if (!(gTasks[taskId].tCounter & 3) && gTasks[taskId].tPointless != 0)
+        gTasks[taskId].tPointless++;
+    if (!(gTasks[taskId].tCounter & 1) && gTasks[taskId].tBg2Y != 0)
+        gTasks[taskId].tBg2Y++;
 
     // Slide Pokemon logo up
-    yPos = gTasks[taskId].data[3] * 256;
+    yPos = gTasks[taskId].tBg2Y * 256;
     SetGpuReg(REG_OFFSET_BG2Y_L, yPos);
     SetGpuReg(REG_OFFSET_BG2Y_H, yPos / 0x10000);
 
-    gTasks[taskId].data[5] = 15;
-    gTasks[taskId].data[6] = 6;
+    gTasks[taskId].data[5] = 15; // Unused
+    gTasks[taskId].data[6] = 6;  // Unused
 }
 
 // Show Rayquaza silhouette and process main title screen input
 static void Task_TitleScreenPhase3(u8 taskId)
 {
-    if ((JOY_NEW(A_BUTTON)) || (JOY_NEW(START_BUTTON)))
+    if (JOY_NEW(A_BUTTON) || JOY_NEW(START_BUTTON))
     {
         FadeOutBGM(4);
-        BeginNormalPaletteFade(PALETTES_ALL, 0, 0, 0x10, RGB_WHITEALPHA);
+        BeginNormalPaletteFade(PALETTES_ALL, 0, 0, 16, RGB_WHITEALPHA);
         SetMainCallback2(CB2_GoToMainMenu);
     }
     else if (JOY_HELD(CLEAR_SAVE_BUTTON_COMBO) == CLEAR_SAVE_BUTTON_COMBO)
@@ -740,30 +793,29 @@ static void Task_TitleScreenPhase3(u8 taskId)
       && CanResetRTC() == TRUE)
     {
         FadeOutBGM(4);
-        BeginNormalPaletteFade(PALETTES_ALL, 0, 0, 0x10, RGB_BLACK);
+        BeginNormalPaletteFade(PALETTES_ALL, 0, 0, 16, RGB_BLACK);
         SetMainCallback2(CB2_GoToResetRtcScreen);
     }
     else if (JOY_HELD(BERRY_UPDATE_BUTTON_COMBO) == BERRY_UPDATE_BUTTON_COMBO)
     {
         FadeOutBGM(4);
-        BeginNormalPaletteFade(PALETTES_ALL, 0, 0, 0x10, RGB_BLACK);
+        BeginNormalPaletteFade(PALETTES_ALL, 0, 0, 16, RGB_BLACK);
         SetMainCallback2(CB2_GoToBerryFixScreen);
     }
     else
     {
         SetGpuReg(REG_OFFSET_BG2Y_L, 0);
         SetGpuReg(REG_OFFSET_BG2Y_H, 0);
-        gTasks[taskId].tCounter++;
-        if (gTasks[taskId].tCounter & 1)
+        if (++gTasks[taskId].tCounter & 1)
         {
-            gTasks[taskId].data[4]++;
-            gBattle_BG1_Y = gTasks[taskId].data[4] / 2;
+            gTasks[taskId].tBg1Y++;
+            gBattle_BG1_Y = gTasks[taskId].tBg1Y / 2;
             gBattle_BG1_X = 0;
         }
         UpdateLegendaryMarkingColor(gTasks[taskId].tCounter);
         if ((gMPlayInfo_BGM.status & 0xFFFF) == 0)
         {
-            BeginNormalPaletteFade(PALETTES_ALL, 0, 0, 0x10, RGB_WHITEALPHA);
+            BeginNormalPaletteFade(PALETTES_ALL, 0, 0, 16, RGB_WHITEALPHA);
             SetMainCallback2(CB2_GoToCopyrightScreen);
         }
     }
diff --git a/src/trainer_hill.c b/src/trainer_hill.c
index 78604f2f49cd..98f5578e30dd 100644
--- a/src/trainer_hill.c
+++ b/src/trainer_hill.c
@@ -650,7 +650,7 @@ void LoadTrainerHillObjectEventTemplates(void)
         eventTemplates[i].localId = i + 1;
         eventTemplates[i].graphicsId = FacilityClassToGraphicsId(sHillData->floors[floorId].trainers[i].facilityClass);
         eventTemplates[i].x = sHillData->floors[floorId].map.trainerCoords[i] & 0xF;
-        eventTemplates[i].y = ((sHillData->floors[floorId].map.trainerCoords[i] >> 4) & 0xF) + 5;
+        eventTemplates[i].y = ((sHillData->floors[floorId].map.trainerCoords[i] >> 4) & 0xF) + HILL_FLOOR_HEIGHT_MARGIN;
         bits = i << 2;
         eventTemplates[i].movementType = ((sHillData->floors[floorId].map.trainerDirections >> bits) & 0xF) + MOVEMENT_TYPE_FACE_UP;
         eventTemplates[i].trainerRange_berryTreeId = (sHillData->floors[floorId].map.trainerRanges >> bits) & 0xF;
diff --git a/src/use_pokeblock.c b/src/use_pokeblock.c
index 1defb73ea943..2aefdedf38e3 100644
--- a/src/use_pokeblock.c
+++ b/src/use_pokeblock.c
@@ -1115,7 +1115,7 @@ static u8 UNUSED GetPartyIdFromSelectionId_(u8 selectionId)
 
 static void LoadAndCreateUpDownSprites(void)
 {
-    u16 i, spriteId;
+    u16 i;
 
     LoadSpriteSheet(&sSpriteSheet_UpDown);
     LoadSpritePalette(&sSpritePalette_UpDown);
@@ -1125,7 +1125,7 @@ static void LoadAndCreateUpDownSprites(void)
     {
         if (sInfo->enhancements[i] != 0)
         {
-            spriteId = CreateSprite(&sSpriteTemplate_UpDown, sUpDownCoordsOnGraph[i][0], sUpDownCoordsOnGraph[i][1], 0);
+            u16 spriteId = CreateSprite(&sSpriteTemplate_UpDown, sUpDownCoordsOnGraph[i][0], sUpDownCoordsOnGraph[i][1], 0);
             if (spriteId != MAX_SPRITES)
             {
                 if (sInfo->enhancements[i] != 0) // Always true here
@@ -1136,20 +1136,24 @@ static void LoadAndCreateUpDownSprites(void)
     }
 }
 
+#define tTimer data[0]
+
 static void SpriteCB_UpDown(struct Sprite *sprite)
 {
-    if (sprite->data[0] < 6)
+    if (sprite->tTimer < 6)
         sprite->y2 -= 2;
-    else if (sprite->data[0] < 12)
+    else if (sprite->tTimer < 12)
         sprite->y2 += 2;
 
-    if (++sprite->data[0] > 60)
+    if (++sprite->tTimer > 60)
     {
         DestroySprite(sprite);
         sInfo->numEnhancements--;
     }
 }
 
+#undef tTimer
+
 static void LoadPartyInfo(void)
 {
     u16 i;
@@ -1611,12 +1615,15 @@ static void LoadConditionGfx(void)
     LoadSpritePalette(&spritePalette);
 }
 
+#define sSpeed   data[0]
+#define sTargetX data[1]
+
 static void CreateConditionSprite(void)
 {
     u16 i;
     s16 xDiff, xStart;
     int yStart = 17;
-    int var = 8;
+    int speed = 8;
     struct Sprite **sprites = sMenu->condition;
     const struct SpriteTemplate *template = &sSpriteTemplate_Condition;
 
@@ -1625,9 +1632,9 @@ static void CreateConditionSprite(void)
         u8 spriteId = CreateSprite(template, i * xDiff + xStart, yStart, 0);
         if (spriteId != MAX_SPRITES)
         {
-            gSprites[spriteId].data[0] = var;
-            gSprites[spriteId].data[1] = (i * xDiff) | 0x20;
-            gSprites[spriteId].data[2] = i;
+            gSprites[spriteId].sSpeed = speed;
+            gSprites[spriteId].sTargetX = (i * xDiff) | 0x20;
+            gSprites[spriteId].data[2] = i; // Unused
             StartSpriteAnim(&gSprites[spriteId], i);
             sprites[i] = &gSprites[spriteId];
         }
@@ -1656,11 +1663,15 @@ static void SpriteCB_Condition(struct Sprite *sprite)
 {
     s16 prevX = sprite->x;
 
-    sprite->x += sprite->data[0];
-    if ((prevX <= sprite->data[1] && sprite->x >= sprite->data[1])
-     || (prevX >= sprite->data[1] && sprite->x <= sprite->data[1]))
+    // Slide onscreen
+    sprite->x += sprite->sSpeed;
+
+    // Check if target position has been reached/surpassed
+    if ((prevX <= sprite->sTargetX && sprite->x >= sprite->sTargetX)
+     || (prevX >= sprite->sTargetX && sprite->x <= sprite->sTargetX))
     {
-        sprite->x = sprite->data[1];
+        // End slide onscreen, become static sprite.
+        sprite->x = sprite->sTargetX;
         sprite->callback = SpriteCallbackDummy;
     }
 }