Trick Room + Superpower SWEEPER!
Level 5 - Inkay @ Berry Juice
Ability - Contrary
Nature - Adamant (+Atk -Sp.Atk)
EVs - 252 HP / 244 Atk / 12 Def
Set a Trick Room to cover from his Speed. Then spam alots of Superpower to increase Attack and Defense with Contrary ability. If any ghost-type appeared, Night Slash then. If a flying-type appeared and you think Close Combat won't do anything, then use Rock Slide.
Berry Juice recovers HP after you use Trick Room.
Try avoiding Special Attackers because Superpower don't boosts Sp.Def and only Def.