The Subspace Emissary is a game mode in Super Smash Bros. Brawl, being the Adventure Mode for the game. The objective of the Subspace Emissary is to pursue the Subspace Army, led by the Ancient Minister, whose objective is to put the whole world into Subspace. After each segment is beaten, their cut-scenes can be found elsewhere in the game. Both representing EarthBound playable characters are put into the story, with them being partnered together at one point.
Ness is first seen saving Lucas from the King Statue by using PK Thunder first before the statue is about to get Lucas, and then PK Flash to stop it. He fights Porky with him. However, Wario comes and ruins the moment, turning Ness into a trophy. His trophy is seen in Wario's vehicle with a princess, soon joined by Luigi. King Dedede however, comes and steals the cart. At this time, special badges are put on him and the princess, although Kirby gets the badge after she is rescued. Later, when all of the other characters are turned into trophies, the he and Luigi are rescued by the badges, saving Dedede as well as most of the others for the second fight against Tabuu, the true antagonist. They win, and the world is saved, mostly thanks to Sonic.
Lucas is first seen running from the King Statue. He soon falls, and is about to be destroyed when Ness comes to the rescue. The statue is revealed be controlled by Porky, and they fight him. They win, but all is not well as Wario appears. He almost turns Lucas into a trophy, but Ness takes the shot for him, turning into a trophy. Lucas escapes, and runs into the Pokémon Trainer at the Ruined Zoo, who is searching for Charizard with his Squirtle. Lucas aids the Trainer in his adventure, and runs into Wario right before they enter the ruins where Charizard is. Hoping to get revenge, the duo fights Wario and win. Lucas helps the Pokémon Trainer capture Charizard, also gaining Ivysaur along the way. After this point, they join the other characters who haven't been turned into trophies to beat Tabuu, the true mastermind behind the plot. He confronts Tabuu with the rest, but is turned into a trophy. At this time, Ness, Kirby, Luigi, and King Dedede come to the rescue, finding the trophies of the fighters. They beat him, especially with the help of Sonic.