After beating the game go to the giant chasm. You will need strength and surf to get through and Kyurem will be deep in the cave. Check out this website for a map:
Hope this helps :)
Kyurem hides in the Giant Chasm, you need to beat the game before you go there, you just need HM Strenght and Surf to get there
How to change your username
How to add a user avatar
Why was my post hidden?
Flags vs Downvotes
Official PokemonDb League
Type a Pokemon name, type, move or ability to see instant results.