After a events of "Super Smash Bros. Ultimate" Mario, Kirby and all fighters finally defeating Galeem and Dharkon when everyone survives and turns themselves back to normal of becoming spirits and they together live in piece and happily, suddenly when a mysterious and powerful unknown enemy and his army invades all of the universe of Smash, Only Mario, Luigi, Peach, Link, Zelda and Kirby are the only ones who has survived and escaped the initial invading.
