this si what I did for mission 9
I put rex about a handwith infront of my lab, the first rush you get with the 5 or 6 zebra ants hurts if you let them get to your hencies gathering coal.
Rex keeps them busy while he kills thme with the tranq shot, the first 2 rushes just rex is enough to kep them at bay. I hurried up and got to lvl 20 and made close to 40 or so porcupine/mountain lions and sent them to the little pennisula with the generator, then what was left I had 12 or so i sent to attack teh middle base this time i am also leveling to 3 and pumping out more prc lions, another 20 or so. i move attack them to the mid base they happen to get hit on up the first big rush that i get and are slaugheterd, luckily they buy me enough time to build soundwave towers, behind a row of upgrade fences. I get lvl 3 and make 14 musk ox archerfish and move attack themt o teh mid base, they easily take out all the southern defenses as well as the right side fo the base before they are destroyed. during that battle I leveled to 4 and upgraded my croc chameleons, as well as my ram lobsters ( the charge makes up for the loss of Hp that ox loberts have) I keep them in reserve untill i have 14 more porc lions who i move attack the base, when that force is halfway to the enemy base i move attack my amphibious assault to teh mid by the time the cutscene happend I am wailing on the enemy main base, Iblah blah cutscene over and I build 6 more ram lobsters for backup and they arrive along with rex (i have rex backing up all my invasion forces by the way for the pakc hunter buff" and in les than a minute the mission is over.
me getting to levle 3; 5 minutes before the other comp and allowing my artileery basically free reign over his southern defenses is what made this one so easy, that and havin just rex defensd my base for the first 4 or 5 minutes byhimself.