A guardian of the master emerald and chaos emeralds, Chaos was a chao until he was exposed to emerald energy, making him the creature he is today
He is the main antagonist of 'Sonic Adventure', appearing in 'Sonic Adventure 2: Battle' as a playable character in the 2-player game modes. Chaos also appears in Sonic battle as playable and, more recently, in Sonic forces as a minor antagonist.
Referred to as a deity many times in the series, Chaos' power is feared and respected throughout the Sonic universe. Chaos is able to become pure liquid to avoid attacks and travel through tight spaces, he can also stretch out his arms to attack opponents from a distance.
Strength: Chaos is consistently stated and shown to be more powerful than someone like Knuckles, even in his 0 form (although much slower than any of the casts). With each emerald Chaos receives he attains more of his inherent power, but even Chaos zero can cause smale scale earthquakes with a strike and hop many meters into the air due to lower leg strength.
Durability: A being made of liquid energy, Chaos Zero is completely bullet proof in base and even when injured can reform himself routinely. He can separate limbs from his body with no ill effect and even if damaged has one of the fastest healing factors in the series. Only after his brain is severely damaged does it feel the need to stay a puddle and retreat. Chaos' durability increases with each emerald and can generate a Knuckles resistant shield in Chaos 2.
Hydrokinesis/Cryokinesis: Chaos has the ability to manipulate water and ice on a masterful scale. In base and C2 forms he can make forceful water bursts, leave puddles that attack unsuspecting enemies, fire stone shattering/house leveling water beams, and morph and reform his body parts to attack with heavy results. Concerning Chaos's Cryokinesis, In base he can instantly freeze the air around moving opponents (trapping them) and insta-freeze large bodies of water/land that dwarf shrines. As Chao's power grows so does his Hydro/Cryo-kinesis, and when he gets 7 chaos emeralds he can instantly flood a metropolis and was classified a Global threat.
Chaos can glide on the air though unknown means, and scale almost any substance to make a quick get away quickly.
When exposed to a chaos emerald, he can absorb it and evolve into a stronger form. The more emeralds he absorbs, the stronger he gets and more he evolves. When he has absorbed all 7 emeralds, he becomes perfect chaos, a monster who can project an energy shield, create tidal waves and cyclones of water, absorb projectiles and release them from it's mouth, and project a super-charged energy blast from it's mouth.