Though not as infamous as many moves, owing to its age and lack of damage, Telekinesis is nevertheless a rather nifty addition to the fifth generation of the Pokemon games. It allows your pokemon to levitate the enemy pokemon, essentially giving it flying-type status without conferring the type; at the same time, however, it also renders the enemy utterly vulnerable to all attacks, regardless of their evasion stat. This is an excellent way to beat up those annoying pokemon who like Minimize, Sand Attack, Double Team and other such moves. So how do you get it?
Telekinesis isn't available for pickup until after you've beaten the Elite Four and the Pokemon League champion. Do that and you'll open up a great deal more of Unova for exploration, including Route 18, just west of Routes 17, 1, and Nuvema Town. You'll need Surf to access these routes. Travel west from Route 1 until you reach the centre of Route 18, a house atop a series of cliffs.
From here, continue west and down to the beach. You'll see a stretch of grass on a small rise, at the north of which is an item ball. Grab the item ball for Telekinesis.