Incredible. Accelgor is the one and only REAL wall breaker.
Accelgor@Bug Gem/Petaya Berry
EVs: 252 SAtk/252 Spe/4 HP
IVs: 0 in both Defenses
Guard Split- Accelgor is the only Pokemon other than Alakazam that uses Guard Split well(all the other Pokemon are things like Shuckle and Carbink.). Let's say a Dusclops comes in and want's to wall you. Use Guard Split and get it out of the way.
Bug Buzz- STAB(and activate Unburden if you are holding the Bug Gem).
Focus Blast- Really nice coverage.
Sludge Bomb/Energy Ball/HP Ice/HP Water- Coverage. I would choose Sludge Bomb if you didn't get the right HP.
I hope I helped :)