Empoleon

Water

Empoleon's good bulk allows it to fulfill the niche of a Stealth Rock setter and Defogger at the same time. Utility in Knock Off and Roar lets it cripple Pokemon like Chansey and phaze Pokemon like Suicune. Its amazing defensive typing gives it a resistance to ten types, an immunity to Poison-type attacks, and an important neutrality to Grass-type attacks. Although Empoleon has an amazing typing, the weakness to Ground-type attacks doesn't do it any favors, since it heavily stacks the weakness to Ground- and Electric-type moves with other balance staples like Toxapex. A lack of recovery outside of Leftovers weakens Empoleon's ability to provide Defog and Stealth Rock support and hinders its opportunity to check massive threats like Mega Diancie because it gets worn down so quickly. Empoleon also has lackluster Defense, so Pokemon like Tapu Bulu take advantage of it easily and it gets chipped at quickly by even weak physical attacks. A bad Speed stat and lackluster offensive stats make it very passive and exploitable. Stallbreakers like Mew and Gliscor take advantage of Empoleon's passive nature, preventing it from doing anything worthwhile thanks to their fast Taunt. Empoleon also has huge competition from other Pokemon like Swampert and Mantine. Swampert provides the same Stealth Rock support while also having an immunity to Electric-type attacks, which lets it check massive threats like Tapu Koko and Magnezone. On the other hand, Mantine offers much more reliable Defog support thanks to its superior bulk and access to Roost. It also provides a very important immunity to Ground-type attacks while still being neutral to Grass-type attacks like Empoleon.