How about snes? gamecube, dreamcast, wii, and nintendo ds all have no more than 7 buttons, which is how many buttons my pane has.
n64, ps1, ps2,sega saturn etc seem to have too many buttons for playing on a cab. If I wanted to use some of these systems for shmups, 2d platformers, and fighters I wonder if it would matter much if I left out L2 and R2 for ps1 and 2, left ouf the shoulder buttons for sega saturn, and n64 has wayy too many buttons. But for fighters, platformers, and shmups I Imagine I can get away with leaving out Z, up c an dright C