Ferrothorn @ Leftovers
Ability: Iron Barbs
Level: 50
EVs: 252 HP / 140 Def / 116 SpD
Relaxed Nature
IVs: 0 Spe
- Gyro Ball
- Bullet Seed
- Protect
- Leech Seed
Leftovers spread: Living hjk from mega lopunny, lele psychic nonspecs 4hko. Generally prefers protect due to leftovers but not neccessary.
Ferrothorn @ Choice Band
Ability: Iron Barbs
Level: 50
EVs: 236 HP / 252 Atk / 20 Def
Brave Nature
IVs: 0 Spe
- Gyro Ball
- Power Whip
- Bullet Seed
- Knock Off/Explosion/Bulldoze
Choice Band Spread: Adjustment allows better living +2 ghost-z from mimikyu
Ferrothorn @ Iapapa Berry
Ability: Iron Barbs
Level: 50
EVs: 252 HP / 100 Def / 156 SpD
Sassy Nature
IVs: 0 Spe
- Gyro Ball
- Leech Seed
- Bullet Seed
- Curse/Thunder Wave/Knock Off/Protect
Spdef 50% berry: More spdef spread for lele, lives guaranteed 5 moonblasts from lele, lives fightinium-z from lele, lives most rolls of max spa modest specs lele hp fire.
Ferrothorn @ Iapapa Berry
Ability: Iron Barbs
Level: 50
EVs: 252 HP / 28 Atk / 124 Def / 100 SpD
Relaxed Nature
IVs: 0 Spe
- Gyro Ball
- Leech Seed
- Bullet Seed
- Curse/Thunder Wave/Knock Off/Protect
Standard 50% berry: Defence for guarantee except 1 roll +2 ghostium-z mimi activates bulky berry, 4hko by breloom mach, 4hko by specs lele psychic, rest in attack
Ferrothorn has more move options shown here, generally curse, twave, knock off, protect can be interchanged in the last slot
A great Reference for Ferrothorn Spreads: https://www.ponz-poke.com/entry/2018/03/23/105738