This Chaos has absorbed six of the Chaos Emeralds. With this much power, it is not in the least bit intimidated by Sonic's attacks. It has no qualms about attacking Dr. Robotnik even! — Official description, Sonic Adventure website
Chaos 6 is dramatically different from any of Chaos' previous forms. It is no longer humanoid, instead vaguely resembling a bloated scorpion/frog-like creature. Over three times Big's height, it has a massive body with two extensions/antennas on its sides, two pair of digit-less legs, and a similar pair of large hind legs bending backwards. It has as well a large mouth with razor sharp teeth and two large eyes aligned vertically on its face with three smaller eyes aligned horizontally on each side. It also has a zigzagged tail with a blunt tip. Running through its hind legs are grey bones, connected in the rear by a pelvis-like bone, with a Chaos Emerald embedded in each of them. In its belly lies its bone-covered core, encircled by four standing bones, each with a Chaos Emerald on top.
Powers and abilities
Unlike its previous forms, Chaos 6 cannot be injured by attacking its head, as the brain is now too deeply situated to be damaged. Chaos' new powers include creating powerful shock waves and trying to inhale enemies to eat them. Chaos 6 is also capable of more advanced shapeshifting that its previous forms, such as turning its body into a container and reshape its body into a pillar with its tail on top to slam enemies with energy while it protrudes several spikes. It can also jump and smash its body into the ground to create huge shockwaves of energy.
Work with the perimeter of the large area, where there are a few rings. Don't get close early in the fight. Chaos 6 begins the fight by trying to suck into its maw. Run and jump against the wind until it subsides. to defeat the monster, First attack and deactivate one of the satellites. Use B button or X button to pick up a deactivated satellite, then run at the monster and press B button or X button again to throw it. If it strikes Chaos, he freezes. When Chaos is frozen attack him. Repeat the process four times to win the fight. When the monster emits long tendrils, stay still until you must move to avoid one. When the tendrils retract, run and jump from the swinging tail.
This boss battle takes place after Sonic's one. To defeat Chaos 6 here, freeze it, then crack it while it's defenseless. Glide away from Chaos 6 until its suction subsides. Attack one of the small satellites and pick it up. Run and use B button to throw it at Chaos 6. When the monster freezes, attack it quickly. It take four hits to knock the beast to bits. When Chaos 6 emits long tendrils, stand still until you must move. When the tendrils retract, Jump and glide away to avoid the swinging tail.
When Chaos 6 advances, aim for the small red target inside it to rescue Froggy. Let the monster get close to improve your aim. Cast beyond the beast so the lure passes through the target. With Big's bull's-eye well past the monster, the lure should hit the mark about halfway up Chaos 6's gelatinous body. Mission accomplished.