Perfect Chaos is a super transformation of Chaos. This form was first attained when Chaos retaliated against Tikal's tribe for their mistreatment of the Chao in pursuit of power. While in this form, Chaos was known as the God of Destruction by ancient peoples.
Wiping out the Knuckles clan
Attack on Station Square
After Chaos gained all 7 Super Emeralds he once again transformed into Perfect Chaos. Chaos attacked Station Square, causing violent flooding. Dr. Eggman appears in his new Egg Carrier, the Eggship Destroyer. Eggman soon discovers Chaos is no longer obedient to him as Perfect Chaos turns its attention to the battleship and destroys it in a single blast from his mouth laser. Tikal managed to weaken Perfect Chaos by preforming a ritual to take away the Super Emeralds from him, and throws them to Sonic so that he can transform into Super Sonic. As Perfect Chaos ans Super Sonic battle Sonic realizes he's only making the Chaos angrier.
As the battle continues Chaos becomes dazed and worn out, Sonic notices this and tries to lure the beast to the power generator where Knuckles is. Chaos chases the super powered hedgehog and attempts to catch Sonic with his jaws. Knuckles manages to get turn the power generator back on and as the power lines spark to life and Sonic hits the beast with a final blow, Perfect Chaos is zapped back into his standard form and the Super Emeralds transform into Chao. A sudden flash of light appears and is revealed to be Tikal, who explains that she and Chaos must return to their own Zone now.