Wailord knowing Dive, considering it's less dense than air. (Although arguably the "Why Game Freak? here is on the Pokedex heights and weights.) Slowbro can learn Withdraw. Yeah, it does have a shell, but fitting in there is going to be quite some feat, especially as it's already occupied by a Shellder. Block has been explicitly stating as involving the arms. Failing that I might expect it to involve general bulk to obstruct an enemy's path. This is not remotely reflected in its distribution, with Nosepass, Exeggcute, Forretress, and Cradily (who is rooted to the spot) being I think particularly egregious examples.