Physically Defensive (Ferrothorn) @ Rocky Helmet / Leftovers
Ability: Rough Skin / Dauntless Shield 
EVs: 248 HP / 252 Def / 8 SpD  
Relaxed Nature  
IVs: 0 Spe  
- Leech Seed  
- Spikes / Stealth Rock
- Protect / Knock Off
- Gyro Ball / Body Press

Specially Defensive (Ferrothorn) @ Leftovers
Ability: Flash Fire
EVs: 252 HP / 4 Def / 252 SpD
Careful Nature
- Spikes / Stealth Rock
- Knock Off
- Leech Seed
- Power Whip / Gyro Ball