Okay, Wesley vs. Mal. I am, naturally, assuming that magic is off-limits in this fight, and that we’re dealing with each character at peak physical and mental condition. Also, for the sake of fairness, only melee combat and, possibly, gunplay will be utilized. Mal is, of course, shit with a blade.
Wesley is unquestionably the superior hand-to-hand combatant. Mal is a good fighter, but his style is much less refined. The same goes for his skills with a gun. He’s good, but Wesley has shown much more intelligence and precision in combat. Also, Wesley doesn’t generally seem to care much about whether he lives or dies, which could work in his favor.
Mal, however, wants very much to survive, and a strong sense of self-preservation can also be a big plus during a fight. It could also be argued that Mal tends to have “luck” on his side, while Wesley’s life has been plagued with “bad luck.”
I see Mal and Wesley beating each other to a bloody pulp, with both of them possibly dying from their injuries. But if I had to give one of them the edge, Mal is dirty and reckless, so I could see him limping away from the fight.
Also, cavemen. Obviously.