-First you'll play as the Gaia Colossus against Dark Gaia. When Dark Gaia opens his hands, hit him with two hands. You can also let him swing his arms and hit him after dodging. Keep hitting him with a normal punch until you finish him off. You'll then play as normal Sonic. Start running through the Gaia Colossus and dodge Dark Gaia's tentacles and bullet attacks. Run to the Speed Dash and hit the correct combination. You must do this three times, once per eye. Finally you will play as Super Sonic. Start collecting rings and attack Complete Dark Gaia's seven eyes. You need at least eleven rings to attack an eye so keep track of your ring count. Start hitting the side eyes and dodging the rocks that are ahead until he opens his middle eye. Attack the eye, look all around for flying rocks, and hit the last eye.
-Use the following strategy to dodge Complete Gaia's six hand attack. When playing as Super Sonic against Dark Gaia, he will try to slash you when he has all his small eyes open. He will then attack with all six claws. During this attack, go just under the big eye in the middle of the slash to a small square you can fit in. You will receive any damage. However, if you get hit, you will lose all your rings and fall into the lava.