Oh, for that, you need to make it a Dark Chao, which requires petting and stuff from either Shadow, Rouge, or Eggman. If it's black(if it's a normal Chao), and has bat wings, then it'll be a Shadow Chao. Of course, you have to get it running animals or green chaos drives. That's what I did, and now I have a 'beginner' Shadow Chao.