Certainly Ozzy, Rinkus, Sierra, Red claw. I also consider Shorty somewhat evil, even though not so much as the former ones. Shorty was not particularly nice to Littlefoot at first, tried to hurt him, and even when he returns in the series, he still pretends, as he has passed the leader challenge, so he will lead the gang right away, leaves few members of the gang behind, and he does not really act to them as a caring friend, and I do not think, that he is so much reformed.