Shadow

Green Hill: a picturesque tropical world with palm trees, cliffs, blue lakes and waterfalls, and also with a recognizable "checkerboard" pattern on the soil.
An alternate reality is a modified version of the original reality itself. Example: Green Hill, but Sonic doesn't exist there.

Knuckles: purple eyes, red echidna; kind, though gloomy

Tails: blue eyes, yellow two-tailed fox; kind, sweet, and smart

Amy: green eyes, pink hedgehog; kind, sweet; wears a red sleeveless dress that reaches to her knees but not lower; has a Piko hammer

Rouge: blue eyes; white bat; kind, though cunning

Sonic: emerald eyes; blue hedgehog; cheerful, energetic; has super speed; loves Shadow

Shadow: Crimson eyes; black hedgehog; sullen, rude; has super speed; Ultimate Life Form; loves Sonic