Don't jump on me if I'm wrong. Would you not need 3/o copper for 200A or 4/o Al. 2/o copper is good for 195 amps. I don't know what kind of load you have on this but voltage drop might another reason to use 3/0.

If the service is on the pole then I would say the #6 EG would meet code. Or you could eliminate the EG and bond the 200a panel if conditions are met.

Tom