How do you get rock smash in Pokemon black 2?

1. Obtain the HM06 Rock Smash from the Driftveil Gym Leader Clay after defeating him.

2. Take the HM to a Pokémon Center and talk to the Move Tutor.

3. Select the Pokémon you want to learn Rock Smash.

4. Pay the required amount of money (1,000 Poké Dollars).

5. The Pokémon will learn Rock Smash.