When entering the Mandlorian cirlce, its REALLY tough to win those fights invloving only fists. To win these easily, equip your armor with the best regeneraion underlay available (Even if it means using other characters to make it). Once in the cirlce, inflict any amount of damage on your opponent, and run around, avoiding him. You'll regenerate your health quickly, and the time limit will go off (Yes, there's a time limit). You will be declared victor for most health.