Pokemon black team help?

You have a pretty big fire weakness. Dragonite is the only one of those who could stand up to Infernape, Volcarona, Charizard, or Heatran. You also lack special attacks entirely save Gengar. I think you'd really benefit from a bulky water type pokemon like Milotic or Tentacruel. Otherwise your movesets are pretty solid. I'd reccomend Ice Shard over Ice Beam on Mamoswine, and possibly another move over Sandstorm since Metagross is your only other pokemon who benefits from Sandstorm.