Background for the Uninitiated:
Dark Super Sonic, sometimes defensively referred to as Dark Sonic, is a powered up form of Sonic featured in the Sonic X episode, "Testing Time." The form is different from Super Sonic in that, instead of glowing gold with red eyes, Dark Super Sonic has empty eyes, and he is completely black- like a highlight-less Shadow. Despite this, he shows greatly increased speed and strength. He is believed to be powered by rage- specifically after seeing Chris "passed out" (in the Japanese version, he was stabbed and was close to death), and only when that rage is calmed does he exit the form.
Due to its nature, and the fact the Chaos Emeralds may have had nothing to do with the form, its very name is disputed. Some call it Dark Super Sonic because of the increased abilities, and the apparent skyward, black quills, supposedly caused by the multitude of False Chaos Emeralds created by the Metarex. Some refer to it as Dark Sonic for the same reason- because it isn't golden, and has no involvement with the real Chaos Emeralds, it is not a "Super" form. Some have noted that it is similar to Darkspine Sonic, as seen in Sonic and the Secret Rings.