Kingdra

Water

Kingdra's claim to fame is in its Swift Swim ability, which allows it to outspeed almost the entire metagame in the rain. The rain will also boost the power of its already strong Water-type STAB attacks, making Kingdra an almost unstoppable wallbreaker as well as a very reliable sweeper, especially against offensive teams that rarely have easy ways to stop it. With access to Draco Meteor and Hydro Pump, Kingdra can deal massive damage to almost any target. While not spectacular, Kingdra has passable bulk, letting it shrug off attacks from most defensive Pokemon, making it safe to 2HKO many walls. That being said, Kingdra is overly dependent on having rain support to function. Without it, Kingdra is useless because it lacks speed and its Special Attack is rather unimpressive. Because of this, Kingdra all but requires at least one more teamslot to have a dedicated and reliable rain setter to reach its full potential.