Its name is misspelled "Ice Colussus" in the Japanese version of the game.
Kingdom Hearts Birth by Sleep
After Hades challenges Aqua to a fight, he reveals his trump card: the Ice Colossus. Hades claims that the rules state that fights do not have to be just one-on-one, and that she can pick someone to assist her as well. Zack volunteers to help, but Aqua says she can handle things on her own. She fights Hades and the Ice Colossus, and she emerges victorious. After the battle, Hades remarks that he needs a "real Titan," revealing the Ice Colossus to be an inferior copy of the actual Ice Titan.
The Ice Colossus is a massive creature made of ice that is similar in appearance to an emaciated human being. It has fairly long arms that end in clawed, four-fingered hands. Its icy ribcage is always visible, and its upper back is lined with tall spikes. Its head is rather small in comparison to the rest of its body. Its blocky mouth is filled with sharp teeth; its eyes are small and barely visible. It has a spiky crest decorating the back of its head and cheeks. Its upper legs are very thin, while its thicker lower legs are frozen to the ground, forcing the Ice Colossus to constantly break and regenerate them to walk.
The Ice Colossus's name refers to its frozen body, while "colossus" is a descriptive term for anything of gigantic size.
The Ice Colossus is a much easier opponent than the Ice Titan. It mainly assists Hades by bombarding Aqua with ice shards, which do minor damage but cannot be deflected, as they can against the Ice Titan. The Ice Colossus can also create shockwaves by punching the ground or stomping, and it can also breathe ice.
Simply dodge its attacks and attack the Ice Colossus's legs until it falls over, stunned. A deck that uses -ga level spells, such as Triple Firaga, should be strong enough to take the Colossus down quickly. Then, it is simply a matter of attacking Hades while dodging his fire attacks.
Aqua can also just attack Hades and avoid the Ice Colossus's attacks, but the Colossus itself should be finished then.
A Time To Chill
The Ice Colossus returns as an optional boss in the "A Time To Chill" battle at the Mirage Arena. It is fought alone and has increased HP, but the battle is similar to the battle at the Coliseum. It is fought after several waves of Unversed, as well as Zack and Hades, have been defeated.