Power Suit Samus
Zero Suit Samus radiates energy, dragging in items and enemies towards her while damaging anyone close enough, then somehow regains her Varia Suit and transforms back into Samus. If enemies are caught, they are given 25-26% damage each in the spin and an extra 10% right when she regains her suit. All hits chaining (with a final contact with her glowing body) can OHKO opponents, but it is very difficult.
The attack deals high knockback but is hard to hit correctly due to its incredibly short range. If there are any pieces of her armor left on the stage, they will disappear as she transforms.
In Event 16: Power Suit ON!, the player, as Zero Suit Samus, must acquire a Smash Ball and use her Final Smash to transform into Samus while being pit against two CPU Zero Suit Samuses.
Zero Suit Samus's Final Smash. Samus loses her Power Suit when she fires the Zero Laser, but she can restore it--that is, she can return from her Zero Suit form to her familiar armored form. That being said, Zero Suit Samus is very quick with great reach, so there are tactical reasons to fight as is. If that's your preference, don't pick up any Smash Balls.
It is similar to the Crystal Flash technique from Super Metroid. In this game, the Crystal Flash was an advanced technique that would refill all of Samus Aran's Energy Tanks, at the cost of 10 Missiles, 10 Super Missiles, and 11 Power Bombs. During the Crystal Flash, Samus could be seen in an orb of light without her suit.
In Metroid: Zero Mission, Samus lost her Power Suit and was unable to recover it. Maintaining her Power Suit active requires an immense amount of concentration, and Samus lost this concentration when Space Pirates shot her gunship down to the barren surface of the planet Zebes. Samus regains her Power Suit when she defeats the Ruins Test on Zebes, a test installed by the Chozo to see whether or not Zero Suit Samus was worthy of wielding a more powerful Legendary Power Suit. Samus's suit is pulled nearly out of thin air, much like her Final Smash.