Kyurem

Kyurem is one of the most versatile Pokemon in the entire UU metagame. With an excellent base 130 Special Attack and decent base 95 Speed, it is very effective as a wallbreaker or a revenge killer, giving both bulky teams and hyper offense teams headaches. Additionally, Kyurem's respectable bulk, surprisingly decent defensive typing, and Pressure allow it to be a formidable PP staller, all while maintaining a strong offensive presence. Kyurem can even get past opposing Steel- and Fairy-types that can switch into its STAB attacks with Earth Power and Flash Cannon, respectively. On the downside, while base 95 Speed is enough for Kyurem to revenge kill with a Choice Scarf, it's fairly lackluster on its own, leaving Kyurem outsped by threats such as Mega Aerodactyl and Cobalion. While Kyurem's typing gives it useful resistances to Grass-, Water-, and Electric-type attacks, it also gives Kyurem weaknesses to Dragon- and Fighting-type moves. This makes Kyurem easily revenge killed, as most Dragon- and Fighting-types such as Hydreigon and Mienshao outspeed it. Kyurem also possesses a nasty weakness to Stealth Rock, meaning it will have trouble switching in, which it must do often if it is running a Choice item. Nonetheless, Kyurem's versatility in UU means it should always be considered for a team of any archetype.