Actually, the move is the special he uses after opening two gates. The first special (no matter who your opponent), is the regular lotus with the kick into the air then wrapping the bandages, etc. Down + X opens a gate (can be done without a full chakra bar). After doing that twice, Lee's health will be drained, but his chakra will fill in about 2 seconds. Use X when it fills and he will teleport to whoever he's targeting and uses the lotus where he kicks the enemy around in the air a bunch.
The move is REALLY powerful, it typically will kill the person in one use. But on the downside, as long as you jump right when the screen flashes, it's really easy to dodge.