From the Super Mario Wiki
Tornado Swing is Luigi's Star Swing in Mario Super Sluggers. When used, Luigi will spin around with his bat and make a tornado that traps the ball. The tornado will travel across the field, stunning anyone it hits momentarily. The tornado will stop after a few seconds, and the ball will land on the ground.
Magikoopas and other characters who have a similar special catch can get the ball from inside the tornado, and get Luigi out.