Basically, there's no easy answer. These questions are kinda silly like that, because there's always variables that you can't simplify. We don't know the full extent or limitations to the Gura Gura, so there are people who will come up with hypothetical scenarios; the "what if x allows y". Hell, assuming it's a 1v1, it's up for interpretation on what that means for Big Mom. All her homies were made using her powers, so can she use all of them, or is she limited to using the ones with her own soul in them, or does that even count as 1v1?
Having typed that, I'm down to debate this. Whitebeard's shockwaves can travel through air, allowing him to hit Prometheus and Zeus. I think it's fair to assume the shockwaves would have some effect on them. Whitebeard's probably gonna be able to take advantage of the terrain of the fight, because, you know, he can cause goddamn EARTHQUAKES, but in terms of physical strength, Big Mom would almost certainly win.