Especially when the character is so obviously broken, like Dark and Shadow Donald. Cheap characters with badly animated move sets, who don't fit in with the rest of the roster, either in look, story, or gameplay - that's the essence of MUGEN.
It's a lot more interesting when observed from a distance.
MUGEN is so great because of OP characters like this. There's a Homer floating around somewhere that is unbeatable. If either player is taking it seriously, the match is forfeit.
Full Disclosure: This Ronald is my favorite character, purely for the closeups. Also the aforementioned Homer, and the Killer Whale.