Psychic was, is, and always will be one of the best moves in the Pokemon games. It was infamous for wiping the floor with the Elite Four in the original game, and though psychic-type pokemon have since been downgraded in overall strength Psychic is still an excellent move. This article will help you find Psychic in Pokemon Black and White 2.
Psychic's much easier to find than most of the TMs containing Pokemon Black and White 2's best moves, but it's also very easy to miss if you don't like to explore. Before you can find it, you'll have to proceed far enough in the game to reach Undella Town, the seaside resort near Undella Bay. Once you've done that much, head north out of town towards Route 13. You'll hit a path along the beach.
Proceed along the beach until you see a blue-haired man searching the sand for items. Head a little bit further north from him, then Surf out into the water to the east, staying north of a small island covered in grass. You'll soon spot a path of light blue water occupied by a fisherman and an item. The item is TM29.