Quoted By:
Nihilego @ Leftovers
Ability: Beast Boost
EVs:74 HP/184 Sp. Attack/252 Speed
Wonder Room (Swaps defense and special defense)
Power Gem
Sludge Wave
Psyshock
Evs put it at 336 sp. attack and 335 speed so the ability will boost it's special attack. This makes up for it not having any boost moves available and the extra evs go into bulk to make up for the lack of recovery.
The main idea of this set is to hit hard and abuse it's natural bulk with wonder room. If a special wall comes in you can use Psyshock or swap defenses and probably get a free kill + boost out of it for things that resist Psyshock. When something can hit you hard physically, wonder room to swap your defenses. This would work really well with sandstorm to further increase your bulk.