It's actually pretty easy. Start out by getting the T-Eng in the barrels on the middle section, grab the grenade launcher, rush over to the other ledge with T-Eng barrels and absorb that. Then wait for Green Eye's weakness bubbles on his sides to be in view and stay around the edges (and middle) of the arena (while dodging it's attacks) so you can pop those. After those are taken care of, get down from the ledges and boost dash to stay directly in front of Green Eye while blasting his face bubbles with the Grenade Launcher. Grab as much of the T-Eng that comes out of the monster as you can and you should be fine.