Misdreavus is both fast, sitting at a nice 19 speed tier, and strong, with it being able to utilise both Nasty Plot and Calm Mind sets. It has enough bulk to where it can't be immediately revenge killed by a scarfer either: its only real check is Munchlax, who can be dealt with options like Will-O-Wisp or Thief. I think it is too much for this tier as it stands