Story Mode: The Return of Subspace. (DaKingOfDogs)

The Return of Subspace is the premade Story Mode in Super Smash Bros. Endless.

Story:

Thousands of years after the events of The Subspace Emissary, a battle between Jibanyan and Hat Kid is taking place in The Forgotten Arena. After selecting a character and winning the battle, a large amount of Yo-kai and Mafia Goons appear to fight. After defeating the enemies, Jibanyan notices a Roughraff and Mafia Goon placing a Subspace Bomb in the center of the stadium. Recalling an old legend, Jibanyan and Hat Kid began to chase down the two troublemakers, but get knocked out of the stadium by Roughraff's headbutt. The Subspace Bomb then explodes.

Hat Kid is knocked into the Subcon Forest, where she must complete trials to prove she is worthy to save the world. After exploring the forest (while also losing her soul and completing a couple contracts along the way), she finds a small arena. After looking around, Snatcher appears and gets tells Hat Kid to give up, and that the world belongs to the legendary deity known as "The Subspace God". After a quick fight, Snatcher tells Hat Kid that total destruction is inevitable, gives her back her soul, and disappears.