As mentioned, the team is weak to scarfed Hydreigon, and is additionally weak to Salamence in general, along with other Dragon-type threats (Haxorus, etc.).
As such, I would suggest a scarfed Mamoswine.
Mamoswine @ Choice Scarf
Ability: Thick Fat
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature...