Utakata's Jinchūriki Forms

Utakata was the jinchūriki of the Six-Tails. He's capable of using the Six-Tails' chakra in various and different levels, and was able to control the power up to the sixth tail. In the past, the Six-Tails has already manifested while protecting his vessel from any harm; but because of his power, he swore to never use it again.

Initial Jinchūriki Form
By using the Six-Tails' chakra, Utakata was capable of releasing its power and as such, turn the tide of battle in his favour. In contrast to Naruto, Utakata's eyes turn yellow while displaying this power, but he doesn't have any other changes like Naruto. With this, his physical power and chakra increase considerably making it possible for him to free himself from any control such as Shiranami's Character Bind Technique. In this form, he displays waves of chakra towards many enemies and is capable of overwhelming them without any problems.

Version 1
By releasing more of the Six-Tails' chakra, Utakata can create a chakra cloak. With it, he can suppress powerful kinjutsu, as done with Hotaru, with no harm to her or to himself.

Version 2
Whilst resurrected, Utakata displayed the ability to enter a "Version 2" form, by moulding the Six-Tails' chakra into a human-like shape around himself. When entering into this form, the sudden increase in chakra was such that it instantly vaporised Killer B's ink clone, which had immobilised him at the time.

In addition to forming a dark chakra cloak around his entire body, his appearance becomes more rounded, like that of the Six-Tails; while his hair still is noticeable covering his left eye, like his regular appearance. With the power granted by this form, Utakata not only manifests all of his beast's six tails, but also becomes able to ooze a highly corrosive, alkaline substance that seemingly makes it more difficult to trap or compress him.

Partial Transformation
While it is unknown how much control Utakata has over the Six-Tails, after his resurrection, he was able to form one of the beasts tails without the use of a chakra cloak.

Full Six-Tails Form
While fighting Kakashi Hatake and Might Guy, Tobi forcefully transformed the revived Utakata into his full Six-Tails form. In this form, he takes on the appearance of the Six-Tails itself and gains the ability to produce a powerful alkali, which can be expelled from the beast's mouth and corrode whatever it makes direct contact with.

In the anime, during the attempted forced extraction of the Six-Tails from Utakata's body by his master, Utakata slipped into his full Six-Tails form and killed Harusame. As a result of this incident, Utakata defected from Kirigakure and developed hatred towards master and student relationships, but it is not known if he was in control of his body during the transformation, or if the Six-Tails own personality instead took over. However, when Utakata later tried to stop Hotaru's kinjutsu, he assumed this form while still retaining control, after asking the Six-Tails to give him the power to stop the technique.