Well for Sp.Def nothing beats Blissey. Her high Sp.Def and insane HP help her soak almost any Special Attacks. Other options include Dusknoir, Cressalia, Tentacruel, etc.
On the Def side the best choices are Skarmory, Forretress, Gliscor, etc. Dusknoir and Cressalia could also work here as well.