Peach Beam

The Peach Beam is the upgraded version of the Star Beam featured in Paper Mario. This attack nullifies the enhanced invincibility of Bowser's Star Rod in Kammy Koopa's special battle arena.

Normally, Mario can use the Star Beam on Bowser to remove Bowser's invincibility from the Star Rod, but Kammy's specially designed arena strengthens the invincibility, blocking the Star Beam. Princess Peach, with some timely advice from the Star Kid Twink after their duel with Kammy, makes a wish to grant more power to the Star Spirits. This wish, along with the wishes of every friendly character in the game, gives the Spirits enough power to match Bowser's strength; this enables them to upgrade the Star Beam into the Peach Beam, which can then stop the Star Rod's power.

Trivia

 * Although the Peach Beam was never seen in the Mario & Luigi series, once in Mario & Luigi: Bowser's Inside Story and Mario & Luigi: Dream Team, Peach and Starlow are seen using their combined powers to stop Bowser.