How do you get sludge wave in Pokemon black 2?

In Pokémon Black 2, you can obtain the move Sludge Wave by teaching it to eligible Pokémon through TM. The TM for Sludge Wave is TM122, which can be found in the game. Specifically, it is located in the post-game area known as the "Pokémon World Tournament" after you defeat the Elite Four and Champion. Make sure to check your Pokémon's compatibility with the TM to teach them the move.