FourthRhyme's Papyrus was mentioned earlier, and I believe in general that while FourthRhyme's characters are actually quite charming, they're heavily unpolished. His Bubsy and Browncoat in particular could've been a lot better than they currently are.
Bubsy is absurdly powerful, with specials moves that are either nearly useless (the charge/dash) or flat-out spam to win (the lightning). Oh, and he has hypers that have success rates depending entirely on luck. Mr. Game and Watch's Judge (if only because he had that move from where most of his moveset came from, and IMO he doesn't feel too Smash in his MUGEN incarnations that have Judge) is really an exception to my dislike of luck-based elements in MUGEN.
Browncoat is a let down mainly for one reason: the imps. You can basically just spam the imps to win, and they're quite cheap since they come out almost instantly and are quite agile. Maybe the hypers should also be a bit faster? I dunno....