Megaman ZX: Zero 3-4 bosses

[Chaoticheroevil]

I know how to get the extra content by using slot 2 since I've already tried it with Megaman Zero 3, but naming the Megaman Zero 4 gba and sav "slot 2" won't work and naming them the exact same name as the ZX rom won't work either because I already named the Zero 3 gba and sav after the ZX rom. I've also tried saving the game (not savestate) while the Zero 3 gba and sav was still inside of the slot 2 folder, then replacing the Zero 3 gba and sav with the Zero 4 gba and sav, then the Zero 3 door stopped working while the Zero 4 door started working, then I learned that saving the game or savestating doesn't matter if the gba game and sav aren't in the slot 2 folder.

So my question is, how do you I make both Zero 3 and 4 gba and saves work at the same time in Megaman ZX to fight the Zero 3 and 4 bosses in that game without having to replace the gba and sav with other?

[Doomsday Forte]

You can't. You can only have one set or the other, not both at the same time.

That said, someone made a ROMhack that does what you need, and doesn't even need the Zero 3/4 ROMs or save files! It'll probably be easier to patch the game on a computer, but you might be able to do it on your phone if it can handle .zip archives. This site will let you get around needing patching software too.