I have found a way to put multiple gameboy roms into a gba rom. This could mean awesome things. Final Fantasy Legends Collection anyone?
I've made it so it just converted multiple roms to a singular gba rom. On boot you just scroll and select the game you want to play Some games don't like this. But so far I've found Dragon Warrior 1, 2 and 3 work, survival kids works, pokemon tcg2 works, final fantasy adventure, legend 1 2 and 3 work.