Okay, so this is my team (I know it's series 8, and restricted mons are allowed. I tried a few like Dusk Mane and Zygarde, they haven't worked out better than the mons I have now.)
Coalossal @ Weakness Policy
Ability: Steam Engine
Level: 50
EVs: 120 Def / 138 SpA / 252 SpD
Calm Nature...