Thanks herb, I also did some testing.
The Pi B uses the Older version of retropie which uses lr-pocketsnes by default. This runs bomberman 3/4/5 fine on both installations. However, the new version uses lr-snes9x-next by default, which doesn’t play bomberman3/4/5 very well.
Unfortunately, pocketsnes seems to not support the multitap adapter while snes9x does. This kinda sucks, because I want to play with more than just 2 players.
So, since I dont actually change any retroarch settings, the differnce seems to be the emulator itself. Any ideas? =/