The Final Battle
From SmashWiki, the Super Smash Bros. wiki
The Final Battle is a single-player event match in Super Smash Bros. for Wii U. The player must choose a character and take on Bowser, King Dedede and Ganondorf. The player has two stocks while the opponents each have one. The opponents' attacks all have large damage multipliers on Hard difficulty.
This event is unlocked by clearing Mechanical Menace. Completing the event unlocks the up path.
Clearing the event on hard difficulty awards 5000G.