Adventure Mode: The Subspace Emissary

The Subspace Emissary is the adventure mode and story of Super Smash Bros. Brawl. This will be entirely single-player. It has been said that The Subspace Emissary will rely on character development, meaning that it involves the characters' individual backgrounds. Mario and Kirby have just finished a battle, finishing it with a handshake. However, Meta Knight's ship, the Halberd, flies over the main stadium. It drops purple smoke onto the ground, which then turn into a group of strange robotic creatures, named Primids. Then, Princess Peach and Princess Zelda, who were watching the match, run down to assist Mario and Kirby. The Subspace Army will be the main antagonist, led by the Ancient Minister. They drop down a Subspace Bomb, which is activated by the R.O.B.s, which then shows a detonation timer, that shows the Bomb will explode in three minutes. Mario hurries to deactivate it, but is defeated by a giant cannonball that hits him out of the stadium. Kirby ponders what to do, and notices Peach and Zelda stuck in cages, being held by a Petey Piranha. Petey proceeds to attack Kirby, by dragging the cages across the ground. Kirby dodges, and the cages slowly weaken. However, Kirby soon realized that he can only save one Princess. What happens to the princess who isn't saved, is unknown. It is unknown what happens afterwards, but the Stadium is eventually drawn into Subspace.

In screenshots of The Subspace Emissary, a Hammer Bro. and Bullet Bills were revealed as enemies. An Arwing was also seen being chased by what looks like the Halberd. Additionally, Fox can be seen running away from a giant sheep-like creature, and several Primids imitate the moves of Samus and Meta Knight. In one of the screenshots, Pit could be seen standing in front of an unseen, glowing woman who is presumed to be the goddess Palutena.