diff --git a/src/battle_dynamax.c b/src/battle_dynamax.c
index 06a26718a978..cdcf05f7dba7 100644
--- a/src/battle_dynamax.c
+++ b/src/battle_dynamax.c
@@ -76,6 +76,10 @@ bool32 CanDynamax(u32 battler)
     u16 species = gBattleMons[battler].species;
     u16 holdEffect = GetBattlerHoldEffect(battler, FALSE);
 
+    // Prevents Zigzagoon from dynamaxing in vanilla.
+    if (gBattleTypeFlags & BATTLE_TYPE_FIRST_BATTLE && GetBattlerSide(battler) == B_SIDE_OPPONENT)
+        return FALSE;
+
     // Check if Player has a Dynamax Band.
     if (!TESTING && (GetBattlerPosition(battler) == B_POSITION_PLAYER_LEFT
         || (!(gBattleTypeFlags & BATTLE_TYPE_MULTI) && GetBattlerPosition(battler) == B_POSITION_PLAYER_RIGHT)))
diff --git a/src/battle_terastal.c b/src/battle_terastal.c
index 6866c6aaad87..a0580a73d210 100644
--- a/src/battle_terastal.c
+++ b/src/battle_terastal.c
@@ -63,6 +63,10 @@ bool32 CanTerastallize(u32 battler)
 {
     u32 holdEffect = GetBattlerHoldEffect(battler, FALSE);
 
+    // Prevents Zigzagoon from terastalizing in vanilla.
+    if (gBattleTypeFlags & BATTLE_TYPE_FIRST_BATTLE && GetBattlerSide(battler) == B_SIDE_OPPONENT)
+        return FALSE;
+
     if (TESTING || GetBattlerSide(battler) == B_SIDE_OPPONENT)
     {
         // Skip all other checks in this block, go to HasTrainerUsedGimmick