Chaos

From Wiki 5A

If you get a game called Sonic Adventure or Sonic Adventure 2 you can find a chao garden as your progressing through the game. If you find a chao garden there will be two eggs and there are three ways to hatch them.

• 1. You can pick up the egg and throw it at the wall but its not recommended if you want it to like you.
• 2. You can leave the eggs for a little bit and they will hatch eventually.
• 3. You can pick up the egg and hold the B button and move the analog stick for about for 10 seconds and put it down and it should start to shake and then it will hatch.

From there you can take care of it and play with it. If you got Sonic Adventure 2 you can evolve your chao into a dark or angel chao and if you do that then you will unlock a dark and hero garden for your chao.