If you're going to use roost I'd also make the item Life orb, which makes the set kinda like a bulky latios
Kyurem @ Never-Melt Ice
EVs: 252 SpA / 4 SpD / 252 Spe
IVs: 0 Atk
- Ice Beam
- Focus Blast
- Earth Power
Idk if this was posted before, but this is a pretty fun Kyurem set to use. Specs is strong, but mispredicts can screw you over. So naturally, a Kyurem that can switch moves can be quite menacing. Nothing is quite as satisfying as watching an opponent switch in their Kyurem answer (whether its a bulky water/Heatran/sp. def Tyranitar) and watching it get blown apart by a follow up Freeze-Dry or appropriate coverage move.
As for the item, I toyed around with Life Orb, but I prefer Never-Melt Ice because you can bluff a Choice Specs and catch the opponent off guard. Kyurem clicks either Ice Beam or Freeze-Dry most of the time anyway, and Earth Power/Focus Blast doesn't really need a boost to dent/kill its targets (Heatran, Tyranitar, Ferrothorn, w/e).
If Earth Power/Focus Blast seems redundant, maybe replace one with Roost for longevity. Of course, pair this with Knock Off/Hazards to get rid of annoying Assault Vest/Boots users.