Tailed Beast Control

Throughout the series, several shinobi, jinchūriki or not, have demonstrated the ability to gain control of one or more of the nine tailed beasts. The cause and effect of this control varies between those capable of doing it.

Jinchūriki
The jinchūriki have the potential to control their tailed beasts through sheer willpower and concentration, but requires a lot of training in order to retain them. If an inexperienced jinchūriki transforms deeper into his or her tailed beast's forms, his or her personality tends to corrode into animal instincts, becoming not only more ferocious in battle, but also increasingly dangerous to his or her friends and allies. The best training spot for a jinchūriki to control his or her tailed beast is at the Falls of Truth. For a jinchūriki to have complete control of the tailed beast within, one must have something to fill in the void within their hearts to give them strength.

According to Gerotora, it is implied that the tailed beasts' power consists of two parts: chakra and will. For example, whenever Naruto Uzumaki drew out a certain amount the Nine-Tails' chakra, its will containing its hatred would fuse along with it, and if Naruto was completely succumbed to the Nine-Tails' influence, the seal would break and the Nine-Tails would be released. To control its power, Naruto must have his own will and heart both very strong and free of hatred, in order to separate the Nine-Tails' will from its chakra completely.

Gaara's control over the One-Tail had increased in the beginning of Part II, where he could create and use its giant arms multiple times.

Upon their resurrection all the previous hosts have displayed remarkable control over their beasts. Yugito was able to partially manifest one tail and was able to enter into her 'Version 2' form and even fully transform into her beast. Rōshi was capable of performing these same feats. Han was able to manifest one tail, enter his 'Version 2' form and even fully transform into the Five-Tails. Utakata was also able to partially manifest one tail as well as enter Version 2 form. Fu was able to manifest two tails and enter 'Version 2' form. She has shown to be quite skilled and agile while in this form, as noted by B and has also shown to be capable of flight while in these forms. However, their control was lacking compared to Yagura and Killer B's, as they became the jinchūriki to have complete control of their tailed beasts. Even though Naruto now has full access and control of the Nine-Tails' chakra, he still hasn't tamed the beast itself.

When a jinchūriki is compatible with his or her tailed beast, the beast can act as his or her partner in battle. According to Killer B, once a jinchūriki has the tailed beast's cooperation and complete control of its chakra, he or she become immune to genjutsu, as the tailed beast can disturb its jinchūriki's chakra flow to break genjutsu. In addition, the tailed beast and its jinchūriki also have to have agreements of trading certain amounts of their own chakra, which can allow the jinchūriki to willingly transform into his or her tailed beast and be able to perform the Tailed Beast Ball without losing any control. Otherwise, the transformation without the tailed beast's cooperation will result in failure, and the tailed beast will then gradually consume its jinchūriki's own chakra whenever he or she uses the beast's chakra, which can kill the jinchūriki.

Non-Jinchūriki
Hashirama Senju, the First Hokage, could completely control the tailed beasts by using his Hokage-Style Sixty-Year-Old Technique — Kakuan Entering Society with Bliss-Bringing Hands, which utilises the power of his Wood Release kekkei genkai to forcibly suppress the tailed beasts' chakra. Yamato would later also acquire this power due to his genetic alteration, however by his own admission, to a lesser extent.

Madara Uchiha, Tobi, and Sasuke Uchiha had all used their Sharingan against the Nine-Tails. While Madara could fully subdue the tailed beast by using his Eternal Mangekyō Sharingan, Tobi curiously used the standard verison of his Sharingan to control it. So far, Sasuke was shown using his Sharingan to only suppress a small amount of the Nine-Tails' chakra within Naruto's subconscious.

In the anime, a filler character, Yūkimaru, was able to partially control the Three-Tails, the former tailed beast of Yagura.