This is the form a Saiya-Jin
will take if he/she looks into a full moon, or an energy orb that matches the
moons power. The only way a Saiya-Jin can obtain this form is if he has a Tail.
Saiya-Jins who are able to do this include: Goku(when young), Vegeta(during Saiyan
Saga), Gohan(during Saiyan Saga and in a few movies).