Cheat Codes and Unlockables: Make the Brawl a Royal Rumble.
Complete Classic Mode in under 20 minutes / Play 70 VS matches to unlock Captain Falcon.
Complete 100 ? man brawl / Play 50 VS matches to unlock Falco.
Complete classic mode on hard difficulty using Link or Zelda / Play 200 VS matches to unlock Ganondorf.
Complete Classic Mode / Complete Event Match 20 / Play 350 VS matches to unlock Jigglypuff.
Defeat Lucario in Adventure Mode using Meta Knight / Complete 5 target tests / Play 100 VS matches to unlock Lucario.
Complete Classic mode on easy difficulty / Play 22 VS matches to unlock Luigi.
Complete Classic Mode / Defeat Marth in adventure mode using any character / Play 10 VS matches to unlock Marth.
Mr. Game & Watch:
Complete Classic mode with every character / Play 250 VS matches to unlock Mr. Game & Watch.
Reflect ten projectiles in battle / Defeat Ness in Adventure Mode with any character / Play 5 VS matches to unlock Ness.
Play 160 VS matches to unlock R.O.B.
Select Zelda while holding down the A button before releasing it at the start of the match to unlock Shiek.
Play 15 matches on Shadow Moses Island Stage / Play 130 VS matches to unlock Solid Snake.
Complete Adventure Mode / Play 300 VS matches to unlock Sonic.
Complete Classic Mode with Link / Play 400 VS matches to unlock Toon Link.
Complete Adventure Mode, and complete Boss Battle Mode using Fox / Play 450 VS matches to unlock Wolf.
Zero Suit Samus:
On the stage select screen, hold down the B button (or R button, on Classic Controllers) and select Samus and your desired stage, before releasing B (or R) to play as Zero Suit Samus.