I'm not 100% sure about the exact order, but I think generally:

Cryo and Anemo are probably up there because of Shenhe and Ganyu, and Xiao.

Then we have Geo and Electro, we have Ningguang, Albedo (we don't know his full power, but he fears one day he will destroy Monstadt), Itto who punched a stone wall without hurting himself, and then in the other side, Yae (full power unknown) and Sara who defeated Itto.

Then Pyro and Hydro. Hydro's strongest in terms of combat is Tartaglia, then we also have Mona who can teleport and predict the future, which would probably give them an advantage over Pyro, if Pyro isn't able to stop her first. I know Pyro has Klee who can literally destroy mountains and Diluc who gave another Harbinger trouble in combat, but Tartaglia has the speed to stop them before they can do anything with his delusion. Then we also have Bennet who impressed even Varka with his combat skills, whose bad luck is likely to affect anyone who gets too close to him on the battlefield...