I agree with Alomomola at C. 267 HP wishes are nothing to laugh at, often bringing sweepers or other pokes with no form of recovery in the red back up to full or close to it. With Heal Bell support, it's a great physical wall that has many chances to Toxic its opponents. I might use Scald over Waterfall in RU. I know, slightly worse Special Attack and pseudo-dual status, but RU has more fearsome physical walls, and some specially defensive pokes, like the Hitmons, would cripple to a burn. I use it in NU and it's amazing. I don't see why C isn't fit for it in RU, even though I've never used it in RU. I'm currently testing Haunter in RU. So far it's working great. With my large sample size of one battle so far, it wrecked and single-handedly made my opponent forfeit. Haunter-Aggron core seems great and I can't wait to try it more. Again, I use Haunter in NU, and it's awesome. I'll probably put it in B or C. Edit: I would like to propose Haunter for C Rank. I think this fits Haunter. Haunter's annoying Sub-Disable set can be a real weapon if used correctly, but of course, there's that notable flaw of Haunter dying to like everything it isn't immune to or quad resists. Haunter has lot of potential, it just needs an opportunity, really.