Nihilego @ Choice Specs  
Ability: Beast Boost  
EVs: 252 SpA / 20 SpD / 236 Spe  
Modest Nature  
IVs: 0 Atk  
- Power Gem  
- Acid Spray  
- Hidden Power [Ice]  
- Psychic  

Heracross-Mega @ Heracronite  
Ability: Guts  
EVs: 24 HP / 252 Atk / 172 SpD / 60 Spe  
Adamant Nature  
- Rock Blast  
- Arm Thrust  
- Bullet Seed  
- Bulk Up  

Aggron @ Aggronite  
Ability: Sturdy  
EVs: 252 HP / 252 Atk / 4 Def  
Naughty Nature  
IVs: 0 SpD / 0 Spe  
- Metal Burst  
- Taunt  
- Heavy Slam  
- Avalanche