A special trait of the Saiyan race (including Halfbreed and Praet) is that of their monkey-like tails. However, while it may seems harmless to the common observer, these tails are the secret behind a powerful transformation. All people with Saiyan blood are usually born with these tails, although the likelihood decreases with each generation. As long as a Saiyan possesses a tail, they are able to transform into what is called the Oozaru state when looking at a full moon. The exact mechanism of this transformation is unknown, but it is triggered by a special type of light wave frequency given off by the full moon.

Transforming into an Oozaru multiplies a Saiyan's powerlevel by 10 but has no stat bonuses. While transformed, a Saiyan can speak normally, though it cannot act normally in some respects, such as being able to wear/remove items. However, while transformed, a Saiyan can use the Oozaru Mouth Cannon, an incredibly powerful and formidable attack.

There is also a more powerful version of this transformation. It is referred to as Golden Oozaru due to the fur of the transformed Saiyan resembling the golden hair of a Super Saiyan. In order to transform in a Golden Oozaru, a Saiyan must first master the Super Saiyan 3 technique (Maxima for a Praet). If they have done so, then the next time the Saiyan is at its base pl during a full moon, the Saiyan will transform into a Golden Oozaru rather than a normal Oozaru. Becoming a Golden Oozaru is also the key to attaining the final form for Saiyans, SSJ4. Because of this, Halfbreeds are unable to transform into Golden Oozaru. Golden Oozaru is among the strongest possible powerlevel multiplier in the game, multiplying the Saiyan's powerlevel by 35.

Praets, being essentially similar but still different than full-blooded Saiyans, possess a variation of the Golden Oozaru form referred to as Magnus Rex- the form of the Great King.

This transformation appears very similar to, if somewhat smaller than, the Golden Oozaru form that pure blooded Saiyans can achieve. The difference is that a slight genetic deviation allows Praets to perform this transformation at will, without the aid of a full moon. While a skilled Praet can use a partial transformation as a gateway to their Ultima form, it takes even greater training and unshakeable discipline to maintain control of the Magnus Rex.

Mastering the Magnum Rex form allows a Praet to maintain their original form even under a full moon.