Showstopper is a special move that appears in Paper Mario: The Thousand-Year Door. Mario can learn this techique once he gets the Garnet Star from the Poshley Sanctum in Chapter 6. It only requires 2 SP to use.
Showstopper is a rather unique special move compared to the others. To use it, the player must press a random set of buttons that appear on the screen. Showstopper has the chance to one-hit ko all enemies on the screen. However, this does not work every time. Showstopper is more effective on early, weak enemies such as Goombas. However, it lose is effectiveness to later enemies such as the enemies in the Palace of Shadow or the later floors of the Pit of 100 Trials. Showstopper is a very risky move to use as it can cost Mario a turn if it should miss an enemy or enemies. Showstopper does not work on bosses.