If you decide to keep Ferrothorn, the moveset you have is terribly inefficent at keeping it alive. Ferrothorn NEEDS Leech Seed. A set like this would be much more benneficial:
Ferrothorn (F) @ Leftovers
Trait: Iron Barbs
EVs: 252 HP / 88 Def / 168 SDef
Sassy Nature (+SDef,-Spd)
-Leech Seed...