Video by PowerPyx!!
Here you meet G (Phase 4) as a final boss at the very end. You have 10 minutes to escape from the lab and have at least four minutes remaining on the clock if you defeat G.
Hurry up with Sherry as fast as you can. In addition, you can find a minigun shortly before the final battle, which makes the whole thing much easier. Always aim for G's eyes and dodge his attacks in time, and you'll easily make it.