I don't believe there is one, nik.

Yeah, I always kill them with Bio Blast when I kill them. This is alot harder though...wouldn't it be better to just complete the game minus the CES requirements the first time like this, and then, once you beat the game, try a CES challenge? Because this just seems super difficult. Not to bash you or anything, but I'm surprised you've made it this far. 0_o;