Dark Sonic

Dark Sonic (Dāku Sonikku) is Sonic's darker form. His first appereance was in the TV show Sonic X when he sees Cosmo scared and Chris is hurt by the Metarex. Sonic uses his anger within him to transform; thus (unlike his regular Super form) Dark Sonic doesn't require Chaos Emeralds to transform. Whilst in this state Sonic showed his fury in the destroying of the two Metarex who hurt Chris. Unlike Alternate Sonic's more destructive super form (as seen in the comics), Dark Sonic seems to be able to recognize his enemies and who he should attack and shouldn't but is noticeably more savage; visciously pummeling two Metarex before violently ripping them apart.

Appearance and colors


Sonic achieved this form by accidentally channeling the power of the Metarex's fake Chaos Emeralds, via his own anger. As such, "Dark Super Sonic" is completely rage driven. He quickly destroys both of the machines the Metarex were using to test Sonic and enjoys doing do (hinted by a mad cackle). Sonic powers down when he is calmed by Dr. Eggman who says Sonic normally acts much better than this. As the emeralds are later destroyed, "Dark Super Sonic" is never seen again. Fans speculate that the form could appear in the games if Sonic channels the negative energy of the Chaos Emeralds. The events leading to Sonic's transformation into "Dark Super Sonic" are paralleled in Sonic and the Secret Rings, resulting in Sonic becoming the extremely similar Darkspine Sonic.

Powers and Abilities
Sonic's speed and attack power are augmented while in this state. Not much else changes, but it's possible that he also had augmented Chaos Powers, as he disappeared several times in his battle with the Metarex, and reappeared right behind them.

Trivia

 * Because that Chaos and Dark Gaia in their negative form are referred to as "perfect", it is not necessarily safe to say that Sonic's form is named "Perfect Sonic". One major concern is the fact that Chaos acted out of anger (similar to Sonic) and he still mutated to what his perfect form would/almost would be if he had absorbed the full power of the Emeralds. The primary reason for Chaos' transformation was the threat to the Chao by the Echidnas. In other words, the "Perfect" in Perfect Chaos refers to the physical mutation, gain in power, and the "mistaken" use of the Chaos Emerald's full power when it was really just the Negative energy of the Chaos Emeralds. As for Dark Gaia, it did not actually use any of the powers of the Chaos Emeralds.
 * Sonic's black coloration in Super Smash Bros. Brawl bears a strong resemblance to Dark Sonic's partially transformed powering up form.