Even though Kyurem is a powerful presence in UU, it shouldn't go beyond BL. It couldn't stand a chance in OU, its weaknesses just won't allow for it to be viable there. As a sweeper, even though its stats look impressive, its movepool is lacking, and even if Focus Blast can take out Steels, its Accuracy is unreliable. Steels such as Registeel, Cobalion, and Durant can easily rid of it, and I don't see any of them coming out of UU. Having no boosting moves other than Hone Claws limits its ability to set up (although a gimmicky Mixed Set consisting of HC/Blizzard/Outrage could work). I can see it being a revenge killer utilizing a Choice Scarf or a powerful Hail sweeper. Kyurem should at least be given a chance in UU, despite its obvious strengths.