As a Shadowcat GOD, the best advice I can give anyone is to not get tunnel vision. Don't fixate on single targets. Run in from the side, drop some Autocannon fire in that guy, turn and pump a PPC into that one, and scoot. I managed to TRASH enemies on Marshes by simply doing this, getting them good and mad at me, and then running an insane, chaotic path back across (LOOK AN INJURED SCAT, LETS KILL IT). Then they find me facing them, smiling, as my teammates all dog-pile.