Midair Stadium is the first stage in Adventure Mode: The Subspace Emissary of Super Smash Bros. Brawl. It is available as soon as a new file for Adventure Mode is created, and contains no orange boxes or other secrets, besides Petey Piranha's boss trophy. Midair Stadium cannot be replayed until Adventure Mode is clear because it is engulfed by Subspace before completion. The Stadium is host to a large crowd of unknown identity, though it can be presumed to be the same crowd that cheers for players during brawls.
Midair Stadium also appears in the How to Play video of Brawl, where it models a battle between Mario and Bowser, similar to the How to Play video of Melee. The stage itself is similar to Pokémon Stadium, without the transformations and platforms.
A cutscene opens the stage, zooming in from afar to Midair Stadium, which floats above the ground. A blue arena can be seen inside. The camera moves to show special guest spectators Zelda and Peach looking on from the crowd. Mario, in trophy form, is tossed into the arena as the crowd roars, and is transformed into fighter form. The same happens with Kirby. A versus screen appears with both Kirby and Mario's faces, and the player is allowed to select whom they shall fight as.
The player is then dropped onto a standard arena in a 1-stock match against the other fighter. After the opposing fighter is KO'd, the battle ends.
In the following cutscene, Pit is shown viewing the battle from Skyworld. After this, Mario/Kirby wins the match and revives Kirby/Mario who was turned into a trophy. After the revival, a shadow covers Midair Stadium. The Battleship Halberd descends through dark red clouds, dropping Shadow Bugs into the Stadium, which form Primids. Zelda uses Farore's Wind to warp to Kirby and Mario, and Peach drops down using a parasol. The player is now allowed to select a character for the next segment between Mario, Kirby, Peach and Zelda.
After all of the enemies are defeated, a new cutscene begins. In the cutscene, the Ancient Minister is introduced as he descends from the Halberd. He drops a Subspace Bomb onto the stadium, and two R.O.B.s activate the device. Mario dashes towards the device in an attempt to deactivate it, but is blown out of Midair Stadium by a cannonball. Kirby turns to watch, hears screaming, and turns back to see Peach and Zelda in cages held by Petey Piranha. Kirby approaches Petey as he roars.
The player must now defeat Petey, the game's first boss. Petey has three attacks. He will either swing Zelda's cage, swing Peach's cage, or leap. All three attacks can be dodged by well-timed jumps. After Petey loses about 2/3 of his health, he will glow red and roar. This indicates a slight increase in the speed of Petey's attacks. To defeat Petey, the player must destroy either Peach's cage or Zelda's cage. Each cage has a separate health bar: attacks to a specific cage decrease its health only. Attacks to Petey himself will damage both cages. Petey dies when the player depletes one of the cage's health bars to zero.
After Petey is defeated, he explodes, and the cages holding the princesses break. Kirby and Zelda/Peach land safely only to watch Wario appear with a Dark Cannon. Wario turns to see a weakened Peach/Zelda and aims the cannon at her. A black arrow comes out of the cannon and pierces her body, turning her into a trophy.
Kirby and Zelda/Peach will attempt to chase after Wario in a bid to save their friend, but Kirby notices that the bomb is about to explode, and then makes his escape with a Warp Star from Midair Stadium before it is consumed by Subspace, taking Zelda/Peach with him.
The stage is cleared after the cutscene, and Kirby and Zelda/Peach will join the team.
It is also used for the fights against Petey Piranha in the Great Maze and Boss Battles.
 Playable Characters
 List of Enemies