Kingdra

Kingdra marks its niche in DPP OU by being the best rain sweeper and an all around vicious attacker. Kingdra's excellent Water / Dragon typing, balanced stat distribution, and Swift Swim make it a terrific Choice Specs user. Kingdra is terrifying under rain and even outside of it, as its strong Water and Dragon STAB moves hits everything neutrally in OU besides Empoleon, it has a decent Speed tier, and bulky Pokemon such as Jirachi, Metagross, and Gyarados struggle to take it on. With rain support, Kingdra outspeeds everything in the tier and a rain-boosted Choice Specs Hydro Pump is really only stomached well by Blissey and Water Absorb Pokemon such as Quagsire and Vaporeon. Even specially bulky Water-resistant Pokemon such as defensive Latias (who is OHKOed by Draco Meteor) and specially defensive Empoleon are 3HKOed. Kingdra's speed and power under rain almost single handedly makes creating a rain infrastructure worth it, as it can mow down offensive teams that don't pack weather changers like Tyranitar and Abomasnow due to outspeeding all relevant Choice Scarf users, being bulky enough to survive priority, and easily 2HKOing even bulkier offensive Water-resistant Pokemon like Gyarados, Dragonite, and Suicune with Hydro Pump.

Kingdra also has access to Dragon Dance and excellent physical offensive options in Waterfall and Outrage. Kingdra's bulk and 4x resistance to Water- and Fire-type moves makes it a great choice on hyper offensive teams alongside Magnezone, as Kingdra can wear down answers to sweepers such as Gyarados and Swords Dance Gliscor and help absorb the defensive burden. Its naturally great coverage in two moves allows it to have a number of different utility moves such as Substitute, Rest, Rain Dance, and even Yawn. Kingdra can also manually set up Rain Dance on more specially offensive sets to act as a weather clearer and power through offensive Pokemon with rain-boosted attacks and the ability to switch moves.

Kingdra is held back by its relatively mediocre stats, reliance on moves with low accuracy or heavy drawbacks, and vulnerability to residual damage. While Kingdra has overall solid stats, it unfortunately isn't outstanding in any department. Base 95 offensive stats really hurts it when trying to use Dragon Dance, as it simply isn't strong enough to overcome walls or even offensive Pokemon that it doesn't hit super effectively. Physically defensive Skarmory, Zapdos, and Celebi all withstand multiple hits from +1 Kingdra, while Metagross, Scizor, and Magnezone can all take at least two hits from it and retaliate—especially if it locks itself into Outrage against these Steel-types. Kingdra's Speed tier at +1 is also mediocre, as it is outsped by most common Choice Scarf users such as Flygon, Rotom-A, Jirachi, Heatran, and Latias and is dealt with accordingly. Its lack of power stat also hurts it on the special side, as it is forced to use moves such as Hydro Pump and Draco Meteor. While using these moves can work when trying to wallbreak, Kingdra unfortunately just isn't strong enough to sweep using the weaker Surf and Dragon Pulse against bulkier targets such as specially defensive Skarmory, Jirachi, and Passho Berry Tyranitar, even when boosted by Choice Specs. This forces it to use more powerful options with drawbacks, where the inevitable miss or being forced out due to the stat drops is catastrophic. Kingdra also is vulnerable to all entry hazards, status, and sand, meaning that if it is forced to switch out it can struggle to get going again, both as a rain sweeper or with Dragon Dance.