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Boo Mario is a form of Mario that debuted the game Super Mario Galaxy. As its name implies, the Boo Mario form is Mario disguised as a Boo, although his hat and face remain respective of his normal form. Boo Luigi, the equivalent form of Luigi, shares the same traits though with his respective features. In Super Mario Galaxy, Luigi has a sorrowful look on his face, though he does not in Puzzle & Dragons: Super Mario Bros. Edition.
In order to become Boo Mario, Mario must grab a Boo Mushroom. With this transformation, Mario can turn himself invisible and pass through certain walls and gates by shaking the Wii Remote, levitate by pressing the button, and descend by holding . The walls Mario can pass through as Boo Mario are similar to the ones he can pass through with Vanish Cap in Super Mario 64. Mario can also understand the language of the Boos, called Booish, meaning bill boards written in that language can be understood by him once he transforms. His Boo form also attracts other Boos, causing them to follow him around and allow him to make use of them for various purposes. The transformation is lost if Mario takes damage, passes through light, touches water, or touches a Launch Star.
Mario first uses this transformation in the Ghostly Galaxy to rescue Luigi. Because Luigi is afraid of ghosts, he cowers when Mario approaches him in Boo form; therefore, Mario must return to his normal form beforehand. It is also used in Boo's Boneyard Galaxy and Sand Spiral Galaxy. This power-up does appear in Super Mario Galaxy 2, but in only one galaxy: the Boo Moon Galaxy in the mission "Haunting the Howling Tower", where the power-up is very widely used.
Boo Mario, as well as Luigi's equivalent form, also appears in Puzzle & Dragons: Super Mario Bros. Edition.
Aside from the games, Boo Mario also appears in animated sticker where it shows Mario defeated, with Boo Mario emerging from him as if Mario had died.
Super Mario Galaxy Trading Card description
In the deep recesses of the Ghostly Galaxy, strange and frightening spirits are after Mario. To help Mario navigate this scary place, he can grab a Boo Mushroom and power up to become Boo Mario! This allows him to become invisible, float like a Boo, and pass through walls.
Super Smash Bros. for Wii U trophy
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