One day, Sonic was defeating the Egg Hornet, when Tails called and said, "Sonic! Du need to watch over a Chao!" Then Sonic asked, "Really? What kind of Chao?" Tails said, "A Dark Chao!" Sonic's jaws dropped. "This isn't gonna be easy!" Sonic exclaimed. "What's his name?" Tails said, "Brian." Sonic said, "I remember him! He's the one I spent 11 hours trying to babysit him! I have to do it again!?" Tails said, "Yep!" Sonic gone to the Dark Garden and saw Brian. "Gulp!" Sonic said. He said, "Hey little guy!" Brian said, "Why do Du care!? I have to go to school even on weekends! The only days I stay Home is on Spring Break, Winter Break, and Summer Break!" Brian, don't be like this, Sonic said, "Everything will be just fine!"
First, hatch a normal (spotted egg) with Sonic. Next, give the Chao green chaos drives with Sonic and Shadow, it will start turning green. (there's a cheat for reusing chaos drives). Then, if Du increase the Chao's stamina to level 6-8, it will eventually evolve, and it will be limette, lime green, 3 spikes, and brown toes. Finally, continue giving it green chaos drives, but with only Sonic. When done, it will be rich blue, and the ears (for some reason) will resemble Sonic. If those are on your Chao, Du have a Sonic Chao!