Fast Attacker (Onix) @ Leftovers
Ability: Rock Head  
EVs: 56 HP / 200 Atk / 252 Spe  
Jolly Nature  
- Earthquake
- Explosion
- Rock Slide
- Toxic / Protect

Substitute + Toxic (Onix) @ Leftovers
Ability: Rock Head  
EVs: 56 HP / 200 Atk / 252 Spe  
Jolly Nature  
- Substitute
- Toxic
- Earthquake
- Rock Slide / Explosion / Protect