Suicune

Huge bulk and a decent defensive typing let Suicune take on the majority of the physical threats in the AAA metagame, and coupled with Calm Mind, this makes Suicune a great wincon for stall and balance that can outlast a lot of its checks because of Scald's burn chance and Poison Heal's recovery. Its great Speed tier for a defensive Pokemon also helps it sweep by allowing Suicune to phaze opposing phazers before they can shuffle Suicune out. However, an overreliance on Scald, due to Suicune's low Special Attack, makes it struggle with foes that don't mind a burn and can hit back in return, such as certain Perish Song users, Skill Swap users like Celebi that can remove Suicune's Poison Heal, Desolate Land users such as Heatran, and Poison Heal users with enough power to break through Suicune. Without Roar, Suicune also may end up as setup fodder for Pokemon that don't mind Scald, such as opposing Suicune and Calm Mind Latios, although Ice Beam also does decent damage to the latter. Finally, its lack of instant recovery holds it back from functioning as a dedicated wall.