Glad to hear it’s (partly) working now!

To switch what emulator is used by Emulation Station just press F4 to quit, and then modify the appropriate COMMAND line in the es_systems.cfg. For Mame that would be :

COMMAND=/home/pi/RetroPie/emulators/RetroArch/installdir/bin/retroarch -L /home/pi/RetroPie/emulatorcores/imame4all-libretro/libretro.so --config /home/pi/RetroPie/configs/all/retroarch.cfg --appendconfig /home/pi/RetroPie/configs/mame/retroarch.cfg %ROM% 
# alternatively: COMMAND=/home/pi/RetroPie/supplementary/runcommand/runcommand.sh 1 "/home/pi/RetroPie/emulators/pifba/fba2x %ROM%" 

Just put a “#” in front of the current COMMAND line above and then add a new one in the same block that points at the emulator you want:

COMMAND = /home/pi/RetroPie/emulators/mame4all-pi/mame %BASENAME%

(you need to use %BASENAME% at the end so that it puts in the rom name without the extension when it tries to launch; Mame is the only one that doesn’t want the extension, so for all other emulators you would put %ROM% instead)

If pifba is just showing a black screen it’s probably because of issues with the roms. You could verify this by running from the command line. IIRC, the roms from romnation worked more consistently than roms from certain other sites. Neo Geo roms also require bios files packaged in a certain way which adds to the complexity.

Not sure how to check the version number of a rom… My best suggestion would be to grab the entire set (mentioned above) via torrent. Not all of those will work but about 90% do.