Just wanting to clarify something... Yes, Vitani kicks Kovu in the face, knocking him backwards, but the kick itself doesn`t make him unconscious, hitting his head against this rock does the trick.
As for who would have won, it`s difficult to say. I`m leaning towards the Pridelanders due to them being well fed and more muscular. However, the Outlanders have years of training on their side, they may be more skilled fighters, but I believe the Pridelanders have greater physical strength and stamina due to not being mal nourished and skinny.
I know that in the film we see the Outlanders attacking the Pridelanders and seemingly having the upper hand (paw?) but the way I see it, they`re illustrating Ziras commands, and it makes it more dramatic when in the beginning of the attack, the Pridelanders seem to be on the losing side. It`s scarier if we`re made to believe that the Outlanders will win.