Pokémon Multi Battle!
From SmashWiki, the Super Smash Bros. wiki
Pokémon Multi Battle is a co-op event match in Super Smash Bros. for Wii U. Player 1 initially controls Pikachu while player 2 starts out with Charizard. The object of the event is to defeat all of the opposite team's Pokémon, which have one stock each. Both teams have the same Pokémon, but the enemy team begins instead with Lucario and Greninja. The battle plays like a 2 stock match, only that each stock is used by a different Pokémon.
Completing the event within 40 seconds awards an X Attack equipment.