Ferrothorn @ Leftovers / Shed Shell  
Ability: Iron Barbs  
EVs: 252 HP / 4 Def / 252 SpD  
Sassy Nature  
IVs: 0 Spe  
- Spikes  
- Strength Sap  
- Gyro Ball / Power Whip
- Leech Seed / Power Whip
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Optional Move(s):
- Toxic
- King's Shield
- Sleep Powder
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Overview:
Ferrothorn's solid bulk and great defensive typing lets it check Primal Kyogre, Zekrom and some Xerneas variants. Its utility moves contains Spikes, Leech Seed and Strength Sap lets it help support its teammates and its decent Attack stat combined with Gyro Ball and Power Whip lets it avoid being passive against Mega Gengar and Primal Kyogre. Its ability is also useful for chipping opponents from using contact moves such as U-turn and Rapid Spin. Its weakness to Fire and Fighting leaves it vulnerable to coverage moves. It is quite slow and is vulnerable to Taunt users.