Azumarill

Azumarill is a potent threat in the OU metagame thanks to its fantastic traits such as typing, bulk, power, and movepool. Its Water / Fairy typing gives it key resistances and immunities to Fire-, Fighting-, Water-, Dark-, and Dragon-type moves, which, when combined with its solid bulk, allows it to sponge many hits and gain free turns. Additionally, its ability, Huge Power, turns its terrible Attack stat into the equivalent of a base 150 Attack stat, ensuring that it's no pushover offensively. It also has a great movepool to complement that. Access to priority in Aqua Jet, powerful STAB moves in Play Rough and Waterfall, and coverage in Knock Off and Superpower ensures that it will always have the right move for the job. These traits allow it to effectively run a Choice Band set, a Belly Drum Set, and an Assault Vest set, each with its own strengths and weaknesses. However, Azumarill has a very low Speed stat, which often forces it to take a hit before attacking, and it is walled by Steel-types unless it's running Superpower, which lowers its Attack and Defense after every use. Additionally, common Electric- and Grass-types, such as Raikou, Thundurus, and Mega Venusaur, are able to check Azumarill, meaning it struggles to do much before these Pokemon are sufficiently weakened.