Kingdra

Though Kingdra is usually seen as a bulky boosting sweeper in UU, it can actually be quite the threat in Ubers. With Kyogre's Drizzle summoning infinite rain, Kingdra will frequently receive doubled Speed from Swift Swim. Its two STABs are great offensively, as they are only resisted by Empoleon, Shedinja, and Ferrothorn. Despite Kingdra's shallow movepool and the fact that it received zero viable new moves in the new generation, its movepool has everything it needs.

However, Ubers is riddled with Dragon-types, so it might be hard for Kingdra to find a team slot. Most Dragon-types in Ubers have ridiculous attacking stats, while Kingdra only has base 95 in both Attack and Special Attack. Even so, Kingdra's Speed is what sets it apart from the other Dragon-types. In addition, it has a resistance to Bullet Punch and a neutrality to Stealth Rock, two things that Rayquaza wished it had. The boost that Kyogre's Drizzle provides for Kingdra's Water-type attacks also somewhat remedies Kingdra's middling Attack and Special Attack. Dragon Dance further improves Kingdra's Attack, and allows it to outspeed everything in Ubers. If you have a rain-centralized team, definitely consider Kingdra for a team slot.