To kill Freiza in any form, charge up your Ki for the Solar Flare attack. Use it close to him, then punch him a few times and repeat. Note: You should be at least level 20 when fighting him.

When you are fighting Freiza's last form, use all your energy with Solar Flare. Hit Freiza ten times. While he is frozen, run away so you do not get hurt. Keep repeating the Solar Flare. Note: You have to be at level 25 to do this. You have to hit him 62 or 72 times.

First, fire an 1/8 of Ki powered blast when you are one step away from being able to hit him with a Kame Hame Ha wave, then move forward one step and start charging the wave. When he gets close, fire and run. This process will have to be repeated.