Toriyama-Sensei? He's not your teacher. You can only say "sensei" if you actually know him. And anyway the characters in DBZ use "KI" and chi. Ki is energy from the world around you. It's not inside of you. Not yet anyway. It's just converted. Think "kinetic"..it turns from potential energy in the atmosphere or chi inside of birds or plants or whatever and comes to you. It's not yours. Anyway...So being a Sayajin increases your capability to use ki. It does stregnthen your chi as well. The characters don't have to use ki. And Goku can be drained of Chi as well. It's happened in the series before. So in the end, yes Goku and Supes can fight without their powers. Martial Arts don't need chi or ki. Certain techniques do but Goku does not have to use them. In fact many times Goku has made himself weaker by lowering his power level. So even if Chi is within him, he can become weaker. Remember when he fought Majin Vegeta? He could have gone SSJ3 anytime but he wanted Vegeta to feel like he was in control. That's why Goku looks away when vegeta questions him.