Pokemon AlteRed is a GBA ROM Hack by kingfin12 based on Pokemon FireRed where all the Pokemon have been replaced with alternate forms.
Pokemon Adventure Red Chapter attempts to follow the Pokemon Adventures manga closely, including nearly every event. Some events were altered to make them long.
Pokemon Let's Go Pikachu & Eevee GBA are a pair of FireRed hacks based loosely on the Switch games but with additional added features like Gen 8 Pokemon.
Download Pre-Patched Pokemon Crystal Advance Redux GBA Rom. It is a continuation/alternate version of the ROM hack, Pokemon Crystal Advance.