What size battery for 2009 Chevy aveo?

The 2009 Chevy Aveo typically uses a Group 35 battery. However, it's always best to check your owner's manual for the specific recommendation from Chevrolet. The manual will list the correct group size and possibly other specifications like cold cranking amps (CCA) for your particular Aveo model (some options might slightly alter requirements). You can also check the battery itself; the group size is usually printed on a label on top.