I think Meta Knight is a pretty great anti-hero, a lot of that comes from how he's wrapped up in mystery and the role he considers himself to have in Dream Land. You always have to be careful with anti-heroes though, the trope has been played up so much that usually they become the most annoying characters, there are so many anti-heroes that are basically "edgy and badass", but because they end up having big fanbases they're forced to work with the good guys because the game/show would lose popularity without them. Shadow and Vegeta are prime examples of this. Usually there's also a lot of moping and doping with them, which really gets to my head, I prefer when characters can work through tough times without crying in a corner for half an hour.
Whether Dark Pit follows that or not I have no idea, I just dislike him because I already dislike Pit, and I'm getting a really "edgy" vibe from him in general, but I haven't actually played Uprising. It's not something either Meta Knight or Dedede follow at all though, so they're not that kind of insufferable worn-out trope.