You need to get to the middle here:
Go left and check the first small rock to the west for a Big Mushroom, and move the boulder in the southwest to get a Star Piece. Inspect the small rocks in the northwest corner for a hidden TinyMushroom, then move the next boulder for a second Star Piece. Check the rocks just east of here for another TinyMushroom, and move the third boulder to find a Comet Shard. When you reach the northeast corner, you have a choice; you can either surf to the southwest, or jump the ledge and shove a fourth boulder. Both ways lead to the staircase at the exit.
The trees and ledges in the crater forest form a natural maze, forcing travelers to move in a clockwise direction. Pick up the Max Elixir to your left and head north. Grab the Max Potion to the right and jump the ledge. A Revive lies in the northwest corner, and a Carbos is just south of it. To the east is a fork in the road with TM13 (Ice Beam) on the southern trail. A Full Heal lies in a patch of dark grass, and a Max Revive is sitting among the trees in the southeast corner. To the northwest is TM03 (Psyshock), in another patch of dark grass. Jump the ledge to the northwest, and follow the trail through the trees to the pit in the middle of the forest. Something cries out when you approach it, and the whole forest is instantly buried under a thick blanket of snow. Go northeast to enter the monster's lair.
The Monster's Lair:
Inside this tiny cave is Kyurem, the third member of the Tao trio. Start off by inflicting double-damage with Fighting-, Rock-, or Dragon-type attacks, then wear down its health with Grass-, Water-, or Electric-type moves. Its signature move Glaciate, while not overly powerful, is guaranteed to reduce the target's Speed, and Endeavor can be brutal as its health is worn away. As the battle takes place in a cave, Dusk Balls are an effective method of capture.
Kyurem is Level 75
His moveset is
- Dragon Pulse
Source: Bulbapedia/ Appendix:Black and White walkthrough/Section 16