Took me a while to get my GBA Roms working because I didn’t know about Linux partition. If you plug your SD card into your Windows PC/laptop you won’t be able to access the proper folder to dump the BIOS.
I had my pi and my laptop on the same network so I used WinSCP (use your Pi’s IP address (default username//password is pi//raspberry) and youll be able to put the BIOS in the proper folder as well as transfer roms easily. (make sure you name the bios the proper name, look at the suggested link above)
I just cannot get Golden Sun: The Lost Age to work properly, it keeps resetting. So if anyone here can give me a solution to that I would be grateful (after naming the character and seeing the intro, it just resets)
If your select button seems to be the only one working in the game, you’ll need to hit F10 and setup the installation of your gamepad in there (one of the two emulators doesn’t read your retroarch settings).
This should be enough to get you going and enjoying your GBA games! Hope it helps.