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 it. If an inexperienced jinchūriki transforms deeper into his or her tailed beast's forms, their 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.

According to Gerotora, it is implied that the tailed beast's power consists of two parts: its chakra and its 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. Yugito Nii also had shown a high level of control, being able to fully transform into the Two-Tails with ease. In the anime, Utakata could assume the form of the Six-Tails as well. However, their control was lacking compared to Yagura and Killer Bee'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 has a strong relationship with his or her tailed beast, the beast can act as his or her partner in battle. According to Killer Bee, 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, according to the Eight-Tails, the jinchūriki and their tailed beasts also have to have agreements of trading certain amounts of their own chakra, which can allow the jinchūriki to willingly transform into their tailed beast and be able to perform the Tailed Beast Ball without losing any control. Otherwise, the transformation without the tailed beasts' cooperation will result in failure, and the tailed beasts will then gradually consume their jinchūriki's own chakra whenever they use the beasts' chakra, which can kill the jinchūriki.

Non-Jinchūriki
Hashirama Senju, the First Hokage, could completely control the tailed beasts using his Hokage-Style Sixty-Year-Old Technique - Kakuan Entering Society with Bliss-Bringing Hands, which utilizes the power of his Wood Release kekkei genkai to forcibly suppress the tailed beasts' chakra.

Madara Uchiha can fully subdue the Nine-Tails using his Eternal Mangekyō Sharingan, and had done it at least twice. When Madara has to control the Nine-Tails, he focuses on the beast's eyes, and the Sharingan will appear over them, and then the Sharingan's tomoe disappears as the pupil enlarges. When Madara had full control, he could then use the Summoning Technique to transport the Nine-Tails to where he wanted it. He has used it once to transport the Nine-Tails right into Konohagakure itself. Sasuke Uchiha had also used his Sharingan against the Nine-Tails within Naruto's subconscious, but only to suppress its chakra.

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