Super Smash Bros. Brawl/Unlockables

Ness

 * Play 5 Vs. matches, then defeat him in battle.
 * Reflect ten projectiles, then defeat him in battle.
 * Complete Stage 29 of the Subspace Emissary and Ness will join your party.

Marth

 * Play 10 Vs. matches, then defeat him in battle.
 * Finish Classic mode on any difficulty level, then defeat him in battle.
 * Complete Stage 8 of the Subspace Emissary and Marth will join your party.

Lucario

 * Play 100 Vs. matches, then defeat him in battle.
 * Beat all 5 difficulties on Target Test for any character.
 * Complete Stage 21 of the Subspace Emissary and Lucario will join your party.

Luigi

 * Play 22 Vs. matches, then defeat him in battle.
 * Beat Classic on any difficulty with no continues, then defeat him in battle.
 * Complete Stage 29 of the Subspace Emissary and Luigi will join your party.

Falco

 * Play 50 Vs. matches, then defeat him in battle.
 * Beat 100-Man Brawl.
 * Complete Stage 18 of the Subspace Emissary and Falco will join your party.

Captain Falcon

 * Play 70 Vs. matches, then defeat him in battle.
 * Beat Classic Mode in under 12 minutes, then defeat him in battle.
 * Complete Stage 20 of the Subspace Emissary and Captain Falco will join your party.

Snake

 * Play 130 Vs. matches, then defeat him in battle.
 * Play 15 Vs. matches on Shadow Moses Island stage, then defeat him in battle.
 * Complete Stage 23 of the Subspace Emissary and Solid Snake will join your party.

R.O.B.

 * Play 160 Vs. matches, then defeat him in battle.
 * Collect 250 trophies, then defeat him in battle.
 * Complete Stage 27 of the Subspace Emissary and R.O.B. will join your party.

Ganondorf

 * Play 200 Vs. matches, then defeat him in battle.
 * Beat Classic Mode on Hard difficulty with Link or Zelda, then defeat him in battle.
 * Keep Link and Zelda alive when you complete Stage 30 of the Subspace Emissary, and Ganondorf will join your party

Mr. Game & Watch
Also you can get pichu by beating boswer 500 times
 * Play 250 Vs. matches, then defeat him in battle.
 * Beat Classic Mode with every character (Note: It is unknown if this means starters only, or including unlockable characters).
 * Mr. Game & Watch may join you when you complete a stage in Subspace Emissary, but it is unknown which stage.

Sonic

 * Play 300 Vs. matches, then defeat him in battle.
 * Beat Classic Mode on any difficulty with 10 characters, then defeat him in battle. (Note: This method is unconfirmed.)
 * Play over 10 hours in VS Mode.
 * Complete Stage 31 of the Subspace Emissary, and Sonic will join your party.

Jigglypuff

 * Play 350 Vs. matches, then beat her in a match.
 * Complete the Subspace Emissary, then return to Stage 18. At the end of the level where you must shoot yourself through barrels, stop on the platform below the new door. Go in and beat Jigglypuff, then finish the stage.

Toon Link

 * Play 400 Vs. matches, then defeat him in battle.
 * After completing Subspace Emissary, finish Classic mode With Link, then defeat him in battle
 * Complete the Subspace Emissary, then return to Stage 9. At the beginning of the level after the first mini-battle with Primids, a new door appears. Go in and beat Toon Link, then finish the stage.

Wolf

 * Play 450 Vs. matches, then defeat him in battle.
 * Beat Boss Battles mode with Fox, then defeat him in battle.
 * Complete the Subspace Emissary, then return to Stage 14. At the end of the second part of the level, go to the bottom of the elevator shaft instead of going into the door and into the new door that appears there. Beat Wolf, then finish the stage.