How can I Improve my Pokemon team? (Pokemon White)?

Your Gurdurr knows rock type moves,but won't help because of its type in the gym so I'd say mostly all you have to worry about for the gym leader is Swoobat LV.33 Unfezant LV.33, and Swanna LV.35. You should just use strong moves . OR You can try to catch a Blitzle and level it up fast with experience share to get a Zebstrika. It's almost impossible to lose if you have him with you against that gym.