Lmao, Luffy was just fine after Apoo's attack, as shown literally two panels later. It's funny that you are trying to use a scene drawn for dramatic effect to support your case.
And Luffy didn't need G4 to defeat Ulti. He needed it to escape her grip, as she had him by both arms from elbow to shoulder. Something she never would have caught him in, in the first place had he not been focusing his attention on Page One at the time. Luffy knocked Hajrudin out in one punch in his base, but couldn't escape his grip either. Does he need G4 to defeat him also?