Silvally @ Life Orb  
Ability: RKS System  
EVs: 252 Atk / 4 SpD / 252 Spe  
Adamant Nature  
- Explosion  
- Crunch  
- Iron Head  
- Swords Dance  
Lead Silvally to SD + Boom.  Other two moves are for coverage vs things like Ghosts and Rocks before Boom. Normal Gem can be run over Life Orb on Silvally if your RM wants it.

Metagross-Mega @ Metagrossite  
Ability: Tough Claws  
EVs: 252 Atk / 4 SpD / 252 Spe  
Jolly Nature  
- Zen Headbutt  
- Thunder Punch  
- Stomping Tantrum  
- Bullet Punch 
Mega Metagross cleans up afterwards.