How do you get a chaos 0 chao

Get any Chao.

Raise it until it has reincarnated 2 times.

Get all the animals (depending on what game you are playing, SADX or SA2B), and give them to your Chao.

Give Dark/Hero fruit if you want it a Angel Chaos, or a Dark Chaos. If not, do not feed it any fruit at all.

After that, it should evolve.

I might have left out some steps, but besides that, it should work.

Extra Info: Do not listen to the "Chaos Drives will prevent it from evolution" myth. It has been proved that it does not work. In the process of the Chaos Chao, you must be very nice to it, and if you want it colored like Chaos, then get a Sky-Blue Chao (Or any colored if desired), and then evolve it into a Nuetral Chaos Chao.