Avalugg

Avalugg is an incredibly bulky physical powerhouse in 1v1, being able to beat every variant of Dragonite and counter impressive physical threats like Landorus-T, Garchomp, Haxorus, and Mega Lopunny. Sturdy combined with Mirror Coat, Superpower, and Stone Edge also lets it beat Choice Specs Greninja, Heatran, and Mega Charizard Y. However, Avalugg loses to many Pokemon able to counteract Sturdy, such as Mega Gardevoir, Mega Charizard X, Pain Split Magearna, and Fake Out users such as mixed Zeraora, Mega Medicham, and Incineroar. Furthermore, many specially offensive Pokemon that Avalugg would otherwise beat with Mirror Coat have ways to PP stall its most effective set due to Choice Band's lock-in, such as Meloetta, Tapu Lele, Mega Slowbro, and Mega Venusaur. Lastly, even with Choice Band, Avalugg's STAB attack in Avalanche only has 60 Base Power if the foe doesn't attack it, meaning it can struggle to break through many physical walls such as Mega Swampert and Clefable.