Zero Suit Samus

Zero Suit Samus is an alternate form of Samus triggered by her Final Smash in Super Smash Bros. Brawl.

When Samus finishes her Final Smash, the Zero Laser, the force of the beam is so strong it causes the Power Suit to fall off, which was seen in the E3 Trailer. Once this happens, she turns into Zero Suit Samus. Now, she is easier to KO. Players can even pick up and throw her dropped armor, which now act similarly to items. Zero Suit Samus is, however, more swift and agile than her armored counterpart. She can now also use a gun that transforms into a laser.

Zero Suit Samus' emblem in the Super Smash Bros. Series is the Screw Attack.

Trivia

 * Zero Suit Samus, as her name suggests somewhat, is taken from Metroid: Zero Mission, where a certain scene forces Samus to wear a jumpsuit rather than her normal suit.
 * Unless Zero Suit Samus' Final Smash allows her to restore her Power Suit, Samus will be stuck as Zero Suit for the rest of the battle.