Power Suit Samus
Zero Suit Samus radiates energy, dragging in items and enemies towards her while damaging anyone close enough, then somehow regains her Power 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 deal an OHKO, but it is very difficult.
The attack hits with high knockback but is hard to hit correctly due to its incredibly short range. If there are any pieces of her armor still on the stage — this can easily be achieved in training mode by making and getting a Smash Ball as Samus, then immediately making another one and breaking it open as Zero Suit Samus — the broken armor pieces will disappear as she changes.
In Event 16: Power Suit ON!, Zero Suit Samus must acquire a Smash Ball and use her Final Smash to transform into Samus. Other Zero Suit Samuses can acquire the Smash Ball but it will not affect the Event status.
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.