Expansion character

An expansion character, also known as downloadable character, or simply DLC, is the concept for a playable character in Super Smash Flash 2 that is not normally accessible in the default game. Instead, these characters are developed separately from the main game, and can be downloaded into the game once finished. With this concept, characters that did not get into the official roster may be added by other developers even after the game finishes development.

There was a forum where users could indirectly/directly develop, suggest and/or discuss expansion characters.

Expansion characters were revealed/shown in old versions of the Smash Flash DOJO!!!, but were all removed with the constant overhauls in the DOJO!!!. Currently, the game does not support expansion characters, as the concept was initially dropped after the game's first major revamp following the 2011 demo, v0.7. However, it has been confirmed that expansion characters will likely become a thing following the release of the final version. There is also evidence of "XP" characters contained within the games' files, as an expansion slot can be hacked into the game (though non-functional).

List of expansion characters
Below is a list of the official expansion characters revealed via the old DOJO!!! versions.

Dark Sonic
Dark Sonic is a dark super transformation achieved by Sonic the Hedgehog in the anime series Sonic X. The multitude of fake Chaos Emeralds and Sonic's intense anger allowed him to achieve this transformation.

Dark Sonic seems to have two forms, a "mid" and a complete transformation. SSF2 uses the latter, where he looks similar to Super Sonic, except his back quills are longer. He has a dark blue aura around him, his eyes have no pupils or irises, and lastly, is fur and skin are black.

Ike
Ike is the central character of Fire Emblem: Path of Radiance and one of the main characters in Fire Emblem: Radiant Dawn. He is the son of Greil and Elena, as well as the older brother of Mist. He is also the leader of the Greil Mercenaries and the first (and only) main character who is not of noble birth.

Ike was planned to appear in SSF2 with custom sprites resembling those from the Fire Emblem games for the Game Boy Advance. His moveset would be based on his moveset from Super Smash Bros. Brawl, in which he wields Ragnell and delivers slow, powerful attacks.

NES Mario
NES Mario is an unofficial term referring to Mario during the events of Super Mario Bros., where Mario and Luigi attempted to stop Bowser's reign of terror by defeating seven False Bowser's and then freeing several Toads imprisoned by the False Bowsers. Mario and Luigi were, afterwards, able to defeat the real Bowser, release Princess Peach, and return her to the people of the.

In SSF2, NES Mario was planned to appear with custom sprites based on his 8-bit appearance from Super Mario Bros., specifically as Super Mario. His moveset would feature his abilities from that game, and it was hinted to feature other classic characters that would appear with their original sprites, including Bowser, an Excitebike racer, and a Medium Invader from Space Invaders.

Roy
Roy is the main protagonist of Fire Emblem: The Binding Blade. He is the son of Eliwood, the main character of Fire Emblem: The Blazing Blade.

Roy's inclusion in Super Smash Bros. Melee marked his very first appearance. His inclusion in Smash also sparked interest in the Fire Emblem series in the West and was responsible for Nintendo's decision to release the games internationally from that point onwards.

Nintendo of Japan had originally intended to make him and Marth playable only in the game's Japanese release, but ultimately decided against that.

In SSF2, Roy's design would be based upon his Melee appearance, although the sprites themselves would not be custom-made. Roy was supposed to speak Japanese, due to the Fire Emblem series' exclusivity to Japan prior to Melee.

Sephiroth
Sephiroth (セフィロス) is the main antagonist of FINAL FANTASY VII, and one of the major antagonists in its extended universe.

In spin-off appearances, Sephiroth is depicted as Cloud Strife's archenemy, and is seen as a symbol of Cloud's troubled past that haunts him. Sephiroth is a former renowned SOLDIER, who became twisted. He is briefly a party member during a flashback, and is both the penultimate and final boss in FINAL FANTASY VII.

Sephiroth was the first expansion character to be revealed for the SSF2, and was supposed to be released in the Summer of 2008/2009. He was said to be fast, and long-ranged, similarly to Marth, from Fire Emblem.