In Other Trivia........now I like that forum. My least favorite type, as in characters I think you meant, are those who have a past that doesn't match up with their personality at all. A boy who's past consisted of constant war wouldn't be the one happy and skipping in the grass, but quiet and filled with strange notions, but then again, there are some like that out there that I like a bit....so honestly, I don't know.
(If I understood wrong and you meant pokemon, then I say Fighting types.....)