Rōshi's Jinchūriki Forms

Rōshi was the jinchūriki of the Four-Tails. Not much is know about Rōshi or his tailed beast, except that it had ability to mix its earth and fire natures, to create lava which it spewed from its mouth. Due to being its jinchūriki, he also possessed this ability. Rōshi was eventually captured by Kisame Hoshigaki and the Four-Tails extracted, causing his death. However, during the events of the Fourth Shinobi World War, he was resurrected and made into a jinchūriki once again, yet the Eight-Tails remarked that his tailed beast felt "different".

Version 2
Whilst resurrected, Rōshi displayed the ability to enter a "Version 2" form, by moulding the Four-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, he also gained prominent tufts of fur along his back and the characteristic horns of the Four-Tails on his forehead. With the power granted by this form, Rōshi not only manifests all of his beast's four tails, but also becomes able to summon even larger torrents of lava than normal almost instantaneously, which can erupt violently upwards from the ground.

Partial Transformation
After being resurrected, Rōshi demonstrated the ability to manifest one of the beast's tails. In this form he can envelop himself in an armour made of lava. The extreme heat generated by his armour is strong enough to burn his opponent, even without coming in direct contact with them.

Full Four-Tails Form
After Kakashi Hatake realised that the six revived Jinchūriki would not use any of the abillities of the Six Paths of Pain, Tobi acknowledged his skills and decided to be more serious, forcefully transforming Rōshi into the the complete form of the Four-Tailed Beast. In this form, Rōshi gains great strenght as shown by how easily he could throw B, in his full Eight-Tailed transformation.