Baiken's strength is comparable to 1.3 petatons of TNT, and
Gamagori's strength is comparable to 1.78 petatons of TNT, so Gamagori is a bit stronger than Baiken. However, Baiken has disjointed attacks using her weapons, and plenty of combat techniques, including an "instant kill" one, so she'd manage well. Gamagori has his own useful techniques like being able to absorb and easily block damage, and
he has whips that he can rapidly swing. Both characters can reach up to kilometers physically. I don't know what Baiken's profile means by how she can reach thousands of kilometers "with attacks" when the specific kinds of attacks listed in the Range section are considered as having less range, but this doesn't matter much, since she can definitely reach 5 feet to attack Gamagori nonetheless, albeit Gamagori would probably have an easier time manipulating Baiken's position by whipping. It's not as though Baiken can't deal with opponents who tend to use longer range in the
Guilty Gear series by blocking, parrying and finding an opening, though. This battle seems pretty fair so far.
Baiken has Class P lifting strength, whereas Gamagori's lifting strength is three ranks lower at Class M, so Baiken would have a devastating throw and Gamagori would be unable to wrap her. Additionally, Baiken seems to be more skilled. Gamagori's profile describes him as having experience in combat and firm dedication as a student council member, whereas Baiken's profile describes her as a skilled fighter who is able to incorporate various weapons into her fighting style along with magic and ki.
I think the battle would be very close, but due to the slight advantages Baiken has, I vote for her winning the battle. I'm willing to switch my vote if I made an oversight, of course.
