-While facing the Super Beast, rather than running straight at him, run around in a circle. When he gets near an explosive barrel, shoot it. It does more damage then the BBG. Watch out for his plasma shooting arm as well. When you're done, Edgar will talk to you, and you get to see him.
-While under attack by the Super Beast, morph into the alien. Shoot parasites and melee him until he calls the first wave of aliens. Use the BBG to kill these aliens (alternately stay in the alien form), but watch out for the Super Beast. If your health gets too low, switch to human and wait until it is safe to return to alien form. Using alien mode is safer because every time you attack the beast your health will refill.