At the moment, Landorus, Excadrill, and Terrakion can all really hammer any of your switch-ins. You may want to consider replacing your Metagross with a common Gliscor set:
Gliscor @ Toxic Orb
Trait: Poison Heal
EVs: 252 HP / 184 Def / 72 Spe
Impish Nature (+Def, -SAtk)
- Earthquake
- Ice...