I use Scrafty, Tentacruel and Gliscor and they work pretty damn well as a defensive core
Bold Nature @Black Sludge, 252 HP, 240 Def, 16 Spd, Ability: Liquid Ooze
-Scald
-Ice Beam
-Toxic/Toxic Spikes/Giga Drain
-Rapid Spin
Impish Nature @Toxic Orb, 252 Hp ,184 Def, 72 Spd, Ability...