The first cutscene shows the game zooming in from far to Midair Stadium. A blue arena is seen inside. The camera moves to show special guest spectators, Zelda and Peach, looking on from the crowd. Mario in his Trophy form, is tossed into the arena as the crowd cheers. He is transformed into fighter form. Kirby is also tossed into the arena and transformed into fighter form. A versus screem appears with both Kirby's and Mario's faces, and the player can choose who to play as. After choosing, the player is dropped onto the arena, in a 1-stock match against the opponent (Kirby/Mario). After the opponing fighter is KOed the battle ends. The following cutscene, Mario/Kirby wins the match and revives Kirby/Mario who was turned into a trophy. After the revival, Pit is shown viewing the battle from Skyworld. After this, a shadow covers Midair Stadium. The Battleship Halberd descends through dark red clouds, dropping Shadow Bugs into the arena, forming Primids. Zelda uses Farore's Wind and Peach uses Parasol dropping down into the arena. Now, players must choose either Zelda, Peach, Mario, or Kirby to play the next segment. After that segment, 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 it. Mario dashes toward the device in attempt to deactivate it, but he is blown out of Midair Stadium by a Cannonball. Kirby turns to watch, hears screaming, and turns back to find Peach and Zelda in cages held by Petey Piranha. Kirby approaches Petey as he roars. Then Kirby must defeat Petey Piranha. After he is defeated, he explodes, and the cages holding the princesses break. Kirby, Peach, and Zelda land safely to find Wario appearing with a Dark Cannon. Wario turns to see the weakened Peach/Zelda and aims at her. A black arrow comes out of the cannon and pierces Peach's/Zelda's body turning her into a trophy. Kirby and Zelda/Peach will attempt to chase Wario, but Kirby notices that the Subspace Bomb is about to explode. He makes his escape from Midair Stadium before it is consumed by the Subspace explosion, taking Zelda/Peach with him. The stage is cleared after the cutscene, and Kirby and Zelda/Peach will join your team.
When playing the first level, which is Midair Stadium, a cutscene appears. When the cutscene is finished, players must pick Mario/Kirby to play as. Then the player will learn some moves and is then ready to fight Kirby/Mario. When Kirby/Mario has been KOed, another cutscene appears showing the Battleship Halberd dropping Shadow Bugs. The Shadow Bugs form into Primids which begins the second segment. In this segment, the player must defeat a number Primids, Boom Primids, Sword Primids, and Spaaks. After this the third cutscene begins. It shows Peach and Zelda trapped in cages held by Petey Piranha. Mario is knocked out of the arena, so players cannot play as Mario. Instead, they must play as Kirby and defeat Petey Piranha. Each cage has its own health. Petey will slash either one of the cages on the ground or leap to different sides of the arena. Each of the three moves can easily be avoided by jumping. After 2/3 of Petey's health is lost, he turns red and roars. Petey increases in speed, so players must be careful. After one of the cages loses all of its health, Petey is defeated. After the fourth cutscene, Wario appears and kills one of the princesses. Kirby escapes from Midair Stadium, carrying the other princess with him.
- Battle with Kirby/Mario- Menu (Super Smash Bros. Melee) plays.
- Battle with Primids and other enemies- Menu 1 plays.
- Battle with Petey Piranha- Airship Theme (Super Mario Bros. 3) plays.
- Boom Primids
- Sword Primids