Nine-Tails Chakra Mode

Nine-Tails Chakra Mode is a heightened transformation  unique to those with Kurama's chakra sealed into them. Naruto Uzumaki, as Kurama's jinchūriki, is able to enter the form using the beast's Yang chakra. Minato Namikaze, having sealed the fox's Yin chakra into his body immediately before his death, has been able to access the form once reincarnated.

Appearance
While this mode is active, Naruto gains a chakra shroud with six magatama around his neck and two distinctive pieces of hair-like horns resembling the Sage of the Six Paths' silhouette along with a swirl design that resembles the Uzumaki clan's symbol. Naruto's chakra shroud is also covered by various other black lines and spiral patterns, which expand further along his body in certain situations. At times, Naruto's shroud gains the additional seals that appear on his hands while in Tailed Beast Mode. The colour of his eyes changes from blue to orange when he is in this form and while the demon fox shroud is red and releases chakra as acidic bubbles, this form's shroud is yellow and releases chakra as flickering flames. While in this form Naruto's chakra signature and smell are different as noted by Neji and Kiba.

When used by Minato, this mode holds resemblance to something in between both of Naruto's two shrouds; while predominately looking like Naruto's Nine-Tails Chakra Mode, Minato's shroud has additional seals on his hands and feet as well an additional magatama design that appears on his collar, causing it to resemble Naruto's shroud in Tailed Beast Mode. When Minato first entered this mode, the bangs at the sides of his face went upwards as well.

Attributes
As with all jinchūriki transformations, the Nine-Tails Chakra Mode gives the user increased strength, speed, and defences. The Nine-Tails Chakra Mode's increases are noticeably superior: Naruto becomes strong enough to push a fully formed Tailed Beast Ball through a multiple layered barrier with just one arm, neutralise White Zetsu with a single kick despite their durability, and, in collaboration with B in his full Eight-Tails form, knock down Tobi's Demonic Statue of the Outer Path with an uppercut. Naruto's speed is so great in this form that Killer B even had trouble determining if he had used the Body Flicker Technique when attacking Kisame. He could even surpass the speed of a fully charged A, as well as blitz the extremely fast Third Raikage before the latter had any chance to react. Naruto's durability is also very high in this form, as he was able to endure extreme heat with only minor burns. He could even withstand the Tenpenchii technique in this form and while the shroud was completely destroyed after this, he only suffered minor physical wounds.

Naruto is also able to use chakra arms while in Nine-Tails Chakra Mode. Like other jinchūriki he can use the arms to improve his dexterity and manoeuvrability, granting him increased means of interacting with his environment and his opponents. More unique to Naruto, he uses the arms as substitutes for shadow clones in his creation of many Rasengan-variants. Instead of needing a shadow clone to help him with shape transformation, he can do both with just one hand, either his own or the hands of his chakra arms. He still needs more than one hand for the nature transformation of the Rasenshuriken, but this also is accomplished without shadow clones. Once the Rasengan-variants are formed, Naruto can then use the chakra arms to deliver them across long distances or, in the case of Rasenshuriken, guide them to their target. Initially, Naruto tried to create a technique related to the Tailed Beast Ball: the Tailed Beast Rasengan. However, he later develops a more effective version of this technique: the Super Mini-Tailed Beast Ball, which is basically a miniature Tailed Beast Ball that he's able to control with the help of a shadow clone.

Like his predecessor, Mito Uzumaki, Naruto gains Kurama's ability to sense negative emotions, something that not even the best sensor-type ninja can do. In addition, he is capable of sensing Kurama's chakra signature, even while he was inside a chakra isolation chamber within the Falls of Truth; as well as the ability to sense other chakra signatures from great distances. Due to having Kurama's Yang chakra in this form, Wood Release techniques will react to the chakra's life-giving properties and mature into full-grown trees within a matter of seconds, either by contact or close range.

Using Nine-Tails Chakra Mode was initially a risk as Naruto had to temporarily "shelve" his own chakra in order to use Kurama's, which allowed the fox to automatically drain Naruto's. If Kurama managed to take all of Naruto's chakra, Naruto would die. Shadow clones provided an additional risk, as Kurama would absorb every portion of Naruto's chakra even faster for each clone he made. Moreover, Naruto also had to be careful about the amount of time he spent in this mode as there was a limit to how much chakra Naruto managed to pull away from Kurama. Despite these risks, once involving himself in the Fourth Shinobi World War, Naruto deployed several shadow clones while he was in this mode and even managed to remain in the form for an entire night. The Eight-Tails says this is because at some point Kurama had purposely stopped taking Naruto's chakra. After Naruto forms a friendship with Kurama these handicaps no longer apply.

Tailed Beast Mode
All jinchūriki can enter Tailed Beast Mode, which grants them all the strength and abilities of their corresponding tailed beast. However, where other jinchūriki become full-scale replicas of their tailed beast, Naruto and Minato enter a form very visually similar to the Nine-Tails Chakra Mode. For Naruto, the shroud parts down the middle and opens up into a full-length cloak (haori), revealing a black undergarment with three magatama on each side of his high collar. His seal's numerous swirl-patterns, which were located all over his body, open out into complete, dark circles. His eyes become red and slitted and his whisker-markings become much thicker, as they do in his early transformations.

Naruto's speed and strength are once more increased in this form, to the point where he was able to deflect five Tailed Beast Balls by simply moving past them. He was strong enough in this mode to take on five tailed beasts at the same time and later fight against Madara's wooden dragon. He was also fast enough to go across the battlefield in the blink of an eye just in time to rescue both Guy and Kakashi. His ability to perform the Rasengan without a shadow clone remains. Additionally, he can transfer Kurama's chakra to others, granting them Version 1-like chakra shrouds that greatly increase the power of their techniques: Hinata Hyūga for example, was able to deflect one of the Shinju's tail arms to the opposite side of the battlefield with a single Eight Trigrams Vacuum Palm. Kakashi Hatake estimated the transfer to be even greater than when Kurama performed it with him, which increased his Kamui three-fold. Naruto can remotely control each individual shroud, such as forming tails for his allies to deflect incoming projectiles. Despite Kurama's contributions, the chakra produced more closely resembles Naruto's than the fox's as noted by C.

Naruto and Minato are able to become full-scale replicas of Kurama. However instead of the flesh-and-blood constructs the other jinchūriki creates, their Tailed Beast Modes are more chakra-based. The Nine-Tails Chakra Mode enlarges into a tailed beast-cloak that recreates Kurama's overall form, while retaining the exact same seals that were previously present on Naruto and Minato's bodies. Both jinchūriki's eyes become slitted when entering this form. As opposed to the normal nature of the chakra, it no longer burns those who touch it. It is also translucent, as Naruto and his father can be seen inside the replica's head for the duration of the transformation. Appearance aside, both jinchiriki gain the usual advantages of Tailed Beast Mode, notably the ability to create powerful shock-waves and perform Tailed Beast Balls. A single tail in this form can completely overpower Madara Uchiha's senjutsu-enhanced complete Susanoo, smash it to the ground and pin it without any trouble. As shown with Naruto, he can even use the tails of this form as chakra arms to interact with other large targets. Naruto can still perform some of his regular techniques in Tailed Beast Mode, such as the Shadow Clone Technique, as well as the Rasengan on a much larger scale in conjunction with Minato.

Naruto cannot maintain Tailed Beast Mode indefinitely because he and Kurama have not yet formed a perfect bond. They are improving: at first they could only last for five minutes, but by the time of the Ten-Tails' revival they extend it to eight minutes.

Sage Tailed Beast Mode
Naruto can also combine his Tailed Beast Mode with Sage Mode to greatly enhance his abilities, giving him a further increase in speed, strength, durability, ninjutsu and taijutsu. The markings of the Sage also reflect on Kurama's tailed beast-cloak as well.

Trivia

 * When first observing Naruto's enhanced chakra shroud while in Tailed Beast Mode from behind, Kakashi Hatake momentarily mistook Naruto for Minato.
 * In the Chikara Arc, despite the fact that Naruto had not yet subjugated Kurama's power, motivated by the Tonika Village orphans' plea to save Dokku and Shiseru, Naruto temporarily assumed an incomplete version of the Nine-Tails Chakra Mode after breaking free from Kurama's influence. During his brief time in the form, Naruto was able to form an incomplete Tailed Beast Rasengan as well. He was also able to enter an imperfect version of the Tailed Beast Mode, in which his seal spread over his body, forming unique markings. Much like Tailed Beast Mode, Naruto's chakra manifested into a replica of Kurama, although it lacked legs and possessed only six tails. In addition to the shroud's tails, Naruto was capable of forming chakra arms to bind his opponents while in this state.