[Drev]

First, ge ta sonic on, raise it to be neutral (treat them with boh Hero and Dark characters), and while doing that, feed it A LOT of green energies/animals. On it's first evolution, it'ss be gren, but the more you feed it later on, it'll turn blue.

Shadow is the same way, bu make him a Dark Chao.

Another funny thing is those aren't the OFFICIAL Sonic and Shadow Chao. The official ones are shiny and are immortal. You had to get them from a convention in Japan, but now you can get them from Gameshark.