Celasteela, Stakataka, and Magearna are great if you have access to them, but if not, then here are some options to consider:
Bisharp (9 resistances, 2 immunities)
Klefki (Mawile but better stats)
Skarmory (two weaknesses, godly defense)
Metagross (big hp, big attack, big defense, big sp. atk, big movepool, big bst)
Scizor (sharp boi has versatile typings in its moveset and lots of attack)
Those are just what I've had success with.