There's lots of ROM hacking software in the Toolbox section of Emulation. Some notable ones I could list right here are HackMew's, PKSV (Script Editor), YAPE (Pokemon Editor), Swampert's, Wichu's Advanced Series (GBA toolbox), AdvanceMap, and the list goes on. Of course, you can always click around and explore the section for more software that you need. Hope you'll be able to find what you're looking for from here on out.