Evolution

At least once in every Chao's life, it will evolve into either a Hero, Dark, or Neutral Chao.  Each type has it's own garden.  Each type of Chao also has it's own look.

Hero Evolution

When you raise your Chao with most Hero characters (Sonic, Knuckles, and Tails) and the Chao grows to like hero characters (Happy, clapping when held, comes running when you whistle, etc.) it will evolve into a Hero Chao.  Hero Chao have halos instead of dots above their heads.  When you get your very first Hero Chao, the Hero Garden will be unlocked. The Hero Garden is located to the left of the normal Chao Garden.  A case of stairs will lead to the enterance of Hero Garden.

Dark Chao

When you raise your Chao with most evil characters (Shadow, Rouge, and Eggman) and the Chao grows to like the evil characters, (Happy, clapping when held, comes running when you whistle, etc.) it will evolve into a Dark Chao.  Dark Chaos have spike balls above their heads instead of dots.  When you get your very first Dark Chao, the Dark Garden will be unlocked. The Dark Garden is lovated to the right of the normal Chao Garden. A case of stairs will lead downward to the enterance of Dark Garden.

Neutral Chao

When a Chao is raised with a balance of good and evil characters, he/she will become a Neutral Chao. Neutral Chao will be pretty simalar to what they're like before they evolve, but they will be adults, not children.  You don't get any extra garden for Neutral Chao.