What size wire needs to come from power pole to upgrade to 200 amp service?

If this is for the aerial service feeders for 200 amp should be either #2 Copper or #4 Aluminum.

You really need to talk to your Power Company about this, unless this is your property.

Usually the power company owns this equipment. In our area, when the Power Company buried the conductors they used #4 just in case the need to increase the service was needed.

Need # 2/0 copper or #4/0 aluminum for underground, generally speaking, depending on several conditions.

If you mean the drop from the pole at the street this is up to the power company. You have no control over this.

Did you have a service changed and you want the power company to replace the drop?

With 99% of 200A service upgrades the power company does not replace or upgrade the drop.