How do you unlock Perfect Chaos battle on Sonic Adventure DX

Beat everyones storyline then you will unlock something called Super Sonic with a golden question mark, pick it then you will fine yourself at the Mystic Ruins, go to Angel Island (the part where the Master Emearld is) you will see Knuckles and Robotnik knocked out on the ground, when this happens you will be at Angel Islands past do what you have to do there, then you will be back then go to the jungle part of Mystic Runins a storyline part will happen then fight Chaos.