* Dark Sonic's first appearance: He was introduced in Sonic the Hedgehog (1991) as the result of Sonic being exposed to the power of the Chaos Emeralds.
* Sonic 3: The main villains of Sonic 3 are Dr. Robotnik and Knuckles.
So, while Dark Sonic has been a recurring character in the Sonic franchise, he doesn't show up in Sonic 3.