Zero Suit Samus

Zero Suit Samus (ゼロスーツサムス, Zero Sūtu Samusu) is Samus Aran in the absence of her Power Suit. Zero Suit Samus first appeared in Metroid: Zero Mission when Samus's ship crashed back on Zebes near the Space Pirate Mothership. While in this suit, Samus takes much more damage but is more agile. She also carries a pistol with her which paralyzes her opponents.

Super Smash Bros. Brawl
In Super Smash Bros. Brawl, Zero Suit Samus will be a playable character. After using her Final Smash move Zero Laser, Samus' Power Suit falls off, causing Zero Suit Samus to appear.

Final Smash
It is unknown whether there is a name for Zero Suit's Final Smash, but when used she turns back into regular Samus.