Sonic Heroes/Other Characters
Froggy: Big's "polliwog pal" who lives with him in the Mystic Ruins. Froggy has been kidnapped by Metal Sonic, along with Chocola Chao. Metal Sonic copies Chaos' data from him.
Chaos: A mysterious liquid lifeform who protects the Chao from harm. He is not shown in the game, but does have a role to play in the game, as Metal Sonic kidnaps Froggy and Chocola and copies Chaos' data from them, as they have both encountered Chaos. Chaos' power allows Metal Sonic to melt into a weird liquid.