Kyūbi Naruto

Kyūbi Naruto is 's Final Smash in Super Smash Flash 2. Naruto's Final Smash is to, almost unwillingly, go into his Kyūbi Form. In this state, he can use the powers of the dreaded Kyūbi no Yōko (九尾の妖狐, "Nine-Tailed Demon Fox"), Kurama, a terrible beast with unheard of power. All of Naruto's techniques are severely overpowered in this form.

However, when used incorrectly, this can be considered one of the least powerful Final Forms in the game - unlike most other Final Forms in the game, Naruto can still flinch from attacks. And, due to the fact he has very little counterattacks (attacks that allows him to stop an opponent's chain strikes) this leaves him easy to exploit by fast yet heavy hitters such as Ichigo, who can slash and keep him flinching and prevent him from using his attacks until his Final Form wears off.

The transformation begins with a powerful burst of fiery Chakra revolving around Naruto, while he awakens his One-Tailed Form. Afterwards, you will control Naruto using the Kyūbi's Cloak. All the physical traits of Naruto are altered, including the black rings that surround the more berserk-looking eyes. In this form, Naruto could use his elongated, sharpened claws instead of his fists, and run at greater speeds on all fours, making him more like a beast.

Very few of his attacks remain the same, while the others become powerful slashes and explosions. He can also tap more deepely into his Tailed Beast's power to skip his Two-Tailed Form and awake his Three-Tailed Form, to use the extremely powerful Akai Rasengan, and the even more menacing Four-Tailed Form, were he is powerful enough to use Tailed Beast-only attacks like the Bijūdama and the Red Chakra Arms.

The Kyūbi Naruto is one of the many Final Forms in the game, which means he is a completely different character who can wander around with more powerful attacks. His transformation deals a 22% damage with decent knockback.

Ground Attacks

 * Standard Attack 1: Slashes forward in front of him with claws. 5%
 * Standard Attack 2: Slashes upwards with claws. 6%
 * Up Tilt: Swipes upwards with his claws. 9%
 * Down Tilt: Low tail whip. 9%
 * Side Tilt: Tackles opponents with his claws outstretched . 13%
 * Forward Smash: Slashes forward with his claws. 13%
 * Up Smash: Does an upwards headbutt. 15%
 * Down Smash: Attacks on all sides with his claws. 14%
 * Dash Attack: Slides forward and slashes in front of him . 13%

Aerial Attacks

 * Neutral Aerial: Attacks with his tail in a full circle. 10%
 * Forward Aerial: Slashes forward in front of him with claws . The move Meteor Smashes if it is sweet-spotted. 16%
 * Back Aerial: Backwards tail attack. 12%
 * Up Aerial: Frontflip Tail attack. 12%
 * Down Aerial: Hurls himself down at opponents with his claws outstretched. 11%

Grabs & Throws

 * Grab: Reaches with the Kyūbi's Red Chakra Arms. So far, the longest grab in the game including Final Forms
 * Pummel : Claws his victim. 3% for first hit, 2% for remaining hits.
 * Forward Throw : Same as Forward Smash. 10%
 * Back Throw : Same as Forward Smash, but backwards. 11%
 * Up Throw : Same as Up Tilt. 11%
 * Down Throw : Throws his opponent with a Headbutt. 8%

Other

 * Ledge Attack: Scratches upwards. 8%
 * 100% ledge attack: None for now.
 * Floor attack: N/A.

Misc.

 * Taunts:
 * Neutral: Kyūbi Naruto surrounds himself in a vortex of swirling red Chakra and growls: "Graawwwr...".
 * Side: Same as Neutral.
 * Down: Same as Neutral.
 * Special Abilities:
 * Can use Guren Shingeki an infinite amount of times.
 * Can jump infinite times.

Origin
In the Naruto universe, the Jinchūriki (人柱力, Power of Human Sacrifice) are ninja that at a very young age, are sealed with extremely powerful and monstruous entities know as Tailed Beasts (尾獣, Bijū) or "Chakra Monsters" (チャクラのバケモノ, Chakura no Bakemono). The immense strength that the tailed beasts possess is tempered by their bestial nature, which restricts them from being intelligent enough to use it effectively, thus when the tailed beasts are sealed within humans, they are able to benefit from the knowledge of their hosts, giving them the ability to better utilise their powers. Because of their power, they were sought out by countless humans throughout the ages, and were usually treated as mere tools to be used or taken, a sentiment they absolutely detest. In addition, they are well aware of their origin and the state of the ninja world.

The Jinchūriki are typically lonely people, viewed by those around them as the tailed beasts that had been sealed within them, leading to prejudice and being hated and feared. However, some Jinchūriki refuse to waver, even though they have been shunned, and they eventually earned respect. Such examples include Naruto Uzumaki, Killer B, Yugito Nii, and Gaara.

The Shinobi world has a total of nine Jinchūriki, all of them with a tailed beast sealed inside them, from the One-Tail (一尾, Ichibi), to the Nine-Tails (九尾, Kyūbi). The Jinchūriki have shown to have access to the tailed beasts' massive chakra reserves and, by training, develop unique fighting styles and use the tailed beasts' considerable abilities: Gaara manipulates sand, Yugito breathes fire, Yagura materialises coral, Rōshi creates and manipulates lava, Utakata creates a corrosive alkali, Fū is capable of flight, Killer B produces ink, and Naruto has quick regeneration and can detect negative emotions. In addition, the Jinchūriki can use the chakra to transform themselves into the likeness of their tailed beasts, which further increases their abilities.

The Jinchūriki have the potential to control their tailed beasts' power, but require intense training and sheer willpower in order to properly wield it. Whenever the Jinchūriki draws out a certain amount of the tailed beasts' chakra, the beasts' very own psyche will fuse along with it, which usually involves an inner struggle between them as the Jinchūriki goes deeper into their tailed beasts' forms. If a Jinchūriki were to completely give into its influence, the seal which contains them will break and the tailed beast will be released. For the Jinchūriki to have complete control, they must find something to fill in the void of loneliness within their hearts to give them strength.

Trivia

 * The Smash Flash DOJO!! incorrectly romanizes his name as "Kyuubi Naruto"("Kyuubi Mode" in the new Dojo).
 * Although Kyūbi Naruto uses a shadow clone to charge the Rasengan in-game, in the anime and manga, he didn't need the help of a shadow clone to do this.
 * In v0.9, sometimes, there's a glitch where Kyubi Naruto can't jump.