*G benefits would not apply to OA operated flights, period. You may be able to get away with an additional bag on an OA flight connecting to/from an A3 flight.

The confusion here is sometimes both airlines "wet lease" each other's aircraft in which case you will need to check weather the A3 flight number is original or a codeshare. The boarding pass will always print the original flight number, not the codeshare flight number.

I imagine if you redeem your miles, it will always come with a bag and your *G status will entitle you to an additional bag. Of couse, this applies to A3 not OA.