I would suggest Cofagrigus if only for one move: Haze.
While neither have a very good offensive presence, esp. when used as a wall, at least Cofagrigus can deal with calm mind/ bulk up stallers.
Cofagrigus also has the rather useful ability in Mummy, so Guts Pokemon like Heracross will have their ability negated.
Cofagrigus @ Leftovers
EVs: 252 HP, 252 Sp. Def, 4 Def
- Shadow Ball
- Pain Split/ Rest
If you have a cleric like Umbreon on your team with Heal Bell, Rest is a more viable possibility.
Dusclops might outweigh Cofagrigus (or most other Pokemon) with Eviolite, but it forfeits leftovers recovery. It could be used for a good Curse set though, which will force your opponent to switch Pokemon. However, it has no reliable method of recovery, as Pain Split isn't reliable in any way.