Real life happened so I couldn't ladder much...and even then I'm completely new to the UU scene, so I was out of my element! (One loss was to a Heliolisk purely because I had no idea what it did! :V ) Forgive me for being bad. I hope to improve!
I used Specs Kyurem for my short battling spree:
Kyurem @ Choice Specs
Ability: Pressure
Shiny: Yes
EVs: 252 SAtk / 252 Spd / 4 SDef
Timid Nature
- Ice Beam
- Draco Meteor
- Earth Power
- Flash Cannon
Hits like an absolute monster. Threatens things like M-Blastoise that want to absorb an Ice Beam with crazy strong Draco Meteors (252 SpA Choice Specs Kyurem Draco Meteor vs. 252 HP / 4 SpD Mega Blastoise: 282-333 (77.9 - 91.9%) -- 31.3% chance to OHKO after Stealth Rock). Earth Power chews through Steels. Flash Cannon doesn't 2HKO Florges, unfortunately, but I ran a Jirachi to deal with her, set up SR, and Wish pass.
Biggest problem I had was that poor Kyurem is SR weak himself. Sure, it's bulky enough to take hits, but when you're losing 25% with each switch-in, you really need Defog, and Wish support never hurts.
I'm preaching to the choir, but just wanted to get my two cents in.
Also Crawdaunt is amazing.