In Super Smash Bros. 4, when performing Power Star, Rosalina will pull out a Power Star which shoots out smaller stars in all directions. The stars will rebound when they hit a surface. These smaller stars are fairly ineffective and can be avoided, but the larger power star will grow in size over the duration of the move. Rosalina is able to move freely a couple of seconds after activating Power Star; she becomes vulnerable to attacks at that time. At the end of the Final Smash, the large star will explode, inflicting high knockback on any nearby characters. If an opponent is knocked into the large star, they will be trapped in it as it expands, receiving potentially 250% damage, and will be knocked back when it explodes. The Power Star will continue to expand even if Rosalina gets KOed or SD's right after she activates the Final Smash.
In Super Smash Bros. Ultimate, the move is renamed as Grand Star. Unlike its previous iteration, Rosalina will summon a Grand Star rather than a Power Star and the smaller stars will launch players into the main star rather than away from it, making it easier to trap opponents in it.
In Rosalina's Final Smash, she summons a Power Star above her head. It launches fighters who touch it and also fires a barrage of smaller stars in all directions, all the while growing bigger and bigger. Even if Rosalina falls off the stage right after activating it, the Power Star will keep attacking her foes until it finally explodes.
Power Stars first appeared in Super Mario 64, and act as collectibles that Mario is required to obtain in order to access more levels. These stars also appear again in the remake Super Mario 64 DS, Super Mario Galaxy, and Super Mario Galaxy 2, but the Power Stars were replaced by Shine Sprites in Super Mario Sunshine and Power Moons in Super Mario Odyssey. The Power Star that Rosalina uses in her Final Smash is based on its design in the Galaxy games.
In the Galaxy games, there are special variants of Power Stars known as Grand Stars. These larger stars are generally found at the final level of each world. The Grand Stars are more powerful than Power Stars, and allow Mario to further progress into new worlds. In Super Mario Galaxy, Grand Stars are used to provide power to the six domes onboard the Comet Observatory. Additionally, a Grand Star serves as Rosalina's emblem throughout the Mario spin-offs, beginning with her appearance in Mario Kart Wii.
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