Master Core

Master Core is the final boss of the Classic mode in Super Smash Bros. for Nintendo 3DS; he's only fought on the difficulty levels 6.0 and higher. During the final battle between the player and both Master Hand and Crazy Hand, once Master Hand gets close to defeat, Crazy Hand leaves, and Master Hand's glove rips open and reveals Master Core. Master Core is hidden under a mass of black particles called Swarm, that take on a variety of different transformations and forms during the battle, each form doing a different attack. Once the Swarm is defeated, the black mass disappears, and reveals Master Core's true form, a colorful ball resembling a Smash Ball.