Unlockable character

An unlockable character is a character that is not available at the start of the game (unlike a starter character), but must be unlocked. Unique criteria must be met in order to unlock a certain character. Typically, the player must accomplish a particular in-game feat and once complete, a message will display: "Warning! Challenger Approaching!" with a silhouette of the character you are about to face. By winning the challenge and defeating your opponent, the character becomes playable.

Characters
* Time required to unlock Mewtwo can be split between players (eg. 2 human players requires 10hrs, 3 human players requires 6hrs 40mins, and four players requires 5hrs).

Super Smash Bros. Brawl
Masahiro Sakurai once stated that he feels that it would be appropriate that third-party, or "guest" characters, like Solid Snake or Sonic the Hedgehog, would be unlockable. This became true when Super Smash Bros. Brawl came out on January 31.

Also, the Smash Bros. DOJO!! has confirmed that all unlockable characters will be unlockable by "playing through" The Subspace Emissary. These characters will be unlocked as you progress through the mode, rather than after completing it. The characters are playable when they show up, and will be playable when you finish the level.

Characters
** Toon Link, Jigglypuff and Wolf are not part of the main plot of Subspace Emissary, you must beat the main story first then revisit certain stages to find them that way. *** Sonic is the only character who can be unlocked 4 different ways.