To hit a super fast serve (with smoke), you have to hit the ball at the very top of the toss.

This is easily acheived by starting with the controller in hand ready to flick downward as if you were cast a fishing pole.

Hit the A button to toss the ball, and when the ball toss reaches its peak, or as it is about to reach the peak, flick the controller down quickly.

If timed correctly, you can master this serve literally everytime.