raptor is my favorite. if you have enough of them, you'll not only gain control of air, you can form a barrier by lining them up and put long range weapons on the behind.
in lvl 4, keep sniping the spiders at the left bottom corner until the enemy's fund is running low like 100. then moboilize your units to the right bottom corner for the final kill.
More details on mission 9...
Round 1: Get the game started and stay out of the turrets' range. Get the planes and tanks ready to strike in the next round.
http://i44.photobucket.com/albums/f31/arigon/BattalionNemesisop09_rd_1.jpg
Round 4: A critical point. You should have eliminated most of the long range weapons by now. Things will get easier at this point.
http://i44.photobucket.com/albums/f31/arigon/BattalionNemesisop09_rd_4.jpg
Here is what I do to beat the mission 9 in normal: use 2 small tanks and raptors to kill the turret on the right, along with the rockers. Take out the left turret by a battlecruiser, and don't let enemy ships get through the bridge. Keep building troops and small tanks until the enemy is getting thin. If you are able to do that you are closed to victory.
 "Battalion: Vengeance"){kind=icon}
 "Endless Zombie Rampage 2"){kind=icon}
 "Battalion: Nemesis"){kind=icon}