Bonus stages

Successfully complete the indicated task to unlock the corresponding stage:

75m: Play as Donkey Kong in 20 Brawls.
Big Blue (from Super Smash Bros. Melee): Play as Captain Falcon in 10 Brawls.
Electroplankton: Successfully complete Event Match #28.
Flat Zone 2: Unlock Mr. Game & Watch.
Frozen Hillside: Brawl in the Halberd stage 10 times.
Great Sea: Unlock Toon Link.
Green Greens (from Super Smash Bros. Melee): Play as Kirby in 20 Brawls.
Green Hill Zone: Unlock Sonic.
Hanenbow (from Electroplankton): Successfully complete the "Flower Blooms In The Echoes" event.
Jungle Japes (from Super Smash Bros. Melee): Brawl in any Melee stage 10 times.
Luigi's Mansion: Play as Luigi in 3 Brawls.
Mario Bros.: Successfully complete Event Match #19 (Wario Bros.).
Pokemon Stadium (from Super Smash Bros. Melee): Brawl in the Pokemon Stadium 2 stage 10 times.
Spear Pillar: Successfully complete Event Match #25 (The Aura Is With Me).