Zero Suit Samus

"Is that all?"

- Zero Suit Samus

Zero Suit Samus is an alternate form of Samus Aran without her Power Suit. In this form, Samus's main weapon is the Paralyzer, a small pistol-like weapon capable of stunning enemies. Although Samus has appeared without her armor in previous Metroid games in a small capacity, the first appearance of Samus wearing her Zero Suit was in Metroid: Zero Mission, which consolidated her appearance and abilities outside the Power Suit.

Initially, in Metroid: Zero Mission, Zero Suit Samus is a very vulnerable and more stealth-based form, but the Super Smash Bros. series enhances her abilities by giving her an extensive, speedy hand-to-hand moveset similar to Sheik, as well as additional weaponry in the form of a Plasma Whip mode for her Paralyzer and, in Super Smash Bros. for Nintendo 3DS / Wii U and Super Smash Bros. Ultimate, rocket-powered Jet Boots that resemble high-heeled stilettos.

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, allowing Zero Suit Samus to be playable. Zero Suit Samus is more swift and agile than her armored form, though lighter and easier to KO. In this state, Samus fights using a gun that can stun opponents and also turn into an energy whip. Zero Suit Samus's standard special move is the Paralyzer, in which she fires a blast from the gun that can stun opponents. Her side special is Plasma Whip, in which she fires a whip to the side that deals more damage at the tip. Her up special is Plasma Wire, in which she fires the whip directly up. Finally, her down special is Flip Jump, in which she does a jump that can be followed up with a kick. Similar to Samus, Zero Suit Samus's grab also uses the Paralyzer's whip, which gives her an extended grab; this and her up and side specials can all be used as tether recoveries.

At the character selection screen, when players select Samus, they can start the battle as Zero Suit Samus by holding the controller's assigned shield button when proceeding to the stage selection screen. Players can also turn into Zero Suit Samus from normal Samus mid-battle by executing her up, down, and up taunts in rapid succession.

By using Zero Suit Samus's Final Smash, Power Suit Samus, she transforms back into her armored form.

The Subspace Emissary
Samus first appears in the Subspace Emissary in her Zero Suit, infiltrating The Research Facility to retrieve her stolen Power Suit. Along the way, she finds Pikachu trapped in a power generator and frees it. Eventually, Samus tracks her Power Suit down, but was stopped by evil copies of it. She defeats them and retrieves her suit. She, along with Pikachu, spends most of the Subspace Emissary in either The Research Facility or The Subspace Bomb Factory. When Samus is selected on the World Map, she can still be turned into Zero Suit Samus by pressing the grab button.

Super Smash Bros. for Nintendo 3DS / Wii U
Zero Suit Samus reappears in Super Smash Bros. for Nintendo 3DS and Super Smash Bros. for Wii U as an independent character, after the removal of in-battle transformation moves. Her overall appearance has been somewhat altered, still using her general design from Metroid: Zero Mission while also taking elements from her appearance in Metroid: Other M. As a result of being a separate character, she has a different Final Smash, Gunship. For her general moveset, she adopts different footwear, her boots now featuring a pair of jet boosters on the heels, which enables her kicking moves to be more powerful and have an electricity effect. These Jet Boots have also replaced her up special move, Plasma Wire, with Boost Kick, which uses the jet heels to boost herself into the air while kicking.

Zero Suit Samus receives significant improvements: her mobility and attack speed are faster, many of her attacks deal more knockback, and her tilt attacks and forward smash deal more damage. However, her overall damage output is lowered.

Zero Suit Samus also has two additional alternate costumes, based upon her appearances during the endings for Metroid: Zero Mission and Metroid Fusion.

Super Smash Bros. Ultimate
Zero Suit Samus returns as an unlockable playable character in Super Smash Bros. Ultimate, retaining many of her moves from the previous installment, as well as continuing to be considered a separate fighter from Samus. For her Final Smash, instead of attacking fighters directly from her Gunship, she rides on top of it while wearing the Power Suit and fires a laser very similar to Samus's Zero Laser from the background, which can be aimed with the on-screen reticle. This makes her one of the few fighters that have appeared since Super Smash Bros. Brawl to have a different Final Smash in each appearance (along with King Dedede, Pit, and R.O.B.).

Zero Suit Samus benefits from universal changes: her mobility is even faster, her short hop timing is reduced, the landing lag in her aerials are reduced, the reintroduction of directional air dodging aids her recovery, and the abilities to use any ground attack out of a run and her aerials on ladders come with merits. However, her damage output has been further decreased, while her weight has also been reduced.

WarioWare series
Zero Suit Samus only appears in the Metroid Big Name Game in WarioWare: D.I.Y. There is a small chance that Samus appears in her Zero Suit after the player defeats the Metroids on-screen, rather than her in her Power Suit.

Samus can also appear without her armor at random in the Metroid microgame in the earlier WarioWare: Touched!, though she uses her sprite from the original Metroid rather wearing than the Zero Suit.

Super Mario Maker
Zero Suit Samus appears as a Costume Mario costume in Super Mario Maker. Her sound effects are taken from Metroid: Zero Mission; the theme that plays when the game is loaded plays when the Mystery Mushroom is collected, the theme that plays when an item is obtained plays when the level is completed, and the death sound is played when the player loses a life with the costume on.

amiibo

 * Samus is far from helpless when her Power Suit is deactivated. With her Zero Suit, she doesn't have the firepower she's famed for but is in full possession of the agility and athleticism she gained through her childhood training with the Chozo. Without the armor, she's also much, much faster. The weapon she carries is a self-protection device known as a Paralyzer that stops enemies cold.

Super Smash Bros. Ultimate Super Smash Blog bio

 * Although not as powerful as Samus, her speed is exceptional! Her Paralyzer not only has the ability to stun opponents, but it can also turn into a whip. For her Final Smash, she dons her suit and fires a powerful laser!

Super Smash Bros. series
All of Zero Suit Samus's quote are from Super Smash Bros. Brawl, and are reused in subsequent Super Smash Bros. games.
 * "You're mine."
 * "Try me."
 * "Is that all?"
 * "Be still."

Trivia

 * The Zero Suit is never actually referred to as such in any Metroid title released prior to Super Smash Bros. Brawl.