I think Lickitung is another great defensive mon that's underrated. It can reach 27 HP and 20 in either of it's defenses. Being a pink blob, it likes to wall stuff, obviously, but lickitung also has amazing physical bulk. A set of Dragon Tail/Wish/Heal Bell/Protect provides your team with amazing support in the form of a 14HP Wish, and status healing with Heal Bell. Dragon tail is a cool move, especially with hazards.