Introduction

Contributors: Bivurnum

You've decided you want to hack a Pokémon GBA ROM. Great! Welcome to the world of gen 3 ROM hacking!

There are two different ways to hack: Binary and Decomps.

Binary: Binary hacking is what most people think of for hacking Pokémon. This is the traditional way of doing things. You take a ROM and use a variety of programs to directly edit that ROM's code. While still useful, binary hacking will not be covered in this guide. We will be using something completely different.

Decomps: The code within a GBA ROM is generally unreadable to most humans. However, the code for both the Emerald and FireRed versions of Pokémon have been decompiled into a programming language that is much easier for people to work with: the C programming language. This allows us to make changes to the code more directly and in more specific ways. Because it is a decomp, we are not working with a ROM directly; we make the changes we want to the code and then compile a brand new ROM that includes our changes. It is thanks to pret that we have these decomps to work with. ("Decomp" is short for "decompilation.")

Here is an overview of the differences between the two hacking methods and the advantages of using a decomp over binary hacking (by LOuroboros).

This beginner's guide is mostly informed by information I have stumbled into over time, as well as my own personal experiences. If anyone has any suggestions for additions or changes to this guide, please send me a message on pokecommunity or on Reddit. You can also contact me if you have any questions about the decomps. I'm no expert, but I'm happy to help however I can.

Next Section: Games With Decomps