Following the incognito of the previous crossover, Tabuu threatens the multiverse, but this time it's worse, this time he's trying to make all the Earths collide and explode. Olimar's ship discovers the mystical being and tries to confront it, which is not a very good idea. Tabuu throws Olimar and the Pikmins too far and he lands in Metroid, where he meets Samus and she tells him that he meets a group of powerful warriors who can help stop this new great threat. Once everyone is reunited, they confront Tabuu. What they don't know is that when Mario and his friends are taken to Samus' ship, Wario and Waluigi sneak into it but this time they are discovered. The Wacky Bros confess everything they have been doing and Mario tells them that he could forgive them if they helped in this fight, which they accept. They apparently manage to defeat Tabuu, but what they fail to do is stop his plan in time. In the end, all the worlds end up coexisting in the same universe.
