Chaos Control is a fighting move, first created by Shadow to defeat Godzilla in space. It warps reality, slowing down time and space to the point that the user can move himself anywhere with a single thought, all before anyone or anything can react.
Chaos Control was first used by Shadow during his battle alongside Super Sonic. The two of them were fighting Godzilla, who had fused with the prototype of the Death Egg, in their Super forms. Sonic had become Super Sonic, and Shadow had become Super Shadow. Instinctively, Shadow used Chaos Control to stop time, allowing Super Sonic to strike Godzilla down once and for all. Using Chaos Control completely sapped Shadow's energy, causing him to fall from space and (presumably) die.
Chaos Control is currently used by Shadow himself, according to rumors, because Shadow apparently survived his fall from space and is currently running around with the seven Chaos Emeralds. This is only a rumor, as the majority of news sources worldwide believe Shadow to be dead.