I think you should replace Ferrothorn with a Lucario, Jirachi, or even Cobalion. You're using Ferrothorn as an attacker which it really shouldn't be used as, because it's stats are more defensively based. If you don't want to switch Ferrothorn out, simply change Ferrothorn so it uses moves such as Leech Seed and Stealth Rock and Give Metagross the Choice Band and switch out Stealth Rock for Zen Headbutt.