Akai Rasengan

Akai Rasengan (赤い螺旋丸, Demon Fox Spiralling Sphere), also called Vermilion Rasengan (朱色螺旋丸) in other games, is the standard special move of Kyūbi Naruto in Super Smash Flash 2.

Under the influence of the Nine-Tails' chakra, Naruto can improve his use of the standard Rasengan and simultaneously make up for his shortcomings in performing the technique. The chakra shroud surrounding him served as the shell to stabilise the Rasengan's chakra. Due to the influence exhibited by the Nine-Tails' chakra, this Rasengan changed from its yellow or blue colour to a purple, orange, or red colour, made stronger than its standard version.

Naruto enters his Three-Tailed Form, creates an equally powerful shadow clone to charge a specially powerful Rasengan, that later launches infront of his opponent. Unlike the normal Rasengan, that pushes the opponent onward, the Yōko Rasengan explodes directly on Naruto's hand, even if Naruto didn't make any contact with the opponent.

Kyūbi Rasengan
Kyūbi Rasengan (九尾螺旋丸 Nine-Tailed Spiraling Sphere) is the fully charged version of the technique. This technique can trap opponents inside it's radius, before blowing them away with incredible knockback, much like the Ōdama Rasengan, red instead of blue, far more powerful and can easily OHKO opponents.

Origin
Used only against Sasuke Uchiha on the "Valley of the End", was powerful enough to counter Sasuke's Habataku Chidori (羽撃く千鳥, Flapping One Thousand Birds). The two techniques clashed and created an hyper-dense chakra sphere that later exploded and destroyed half valley on the process.

Trivia

 * In the Anime and Manga, Kyūbi Naruto is able to perform the Rasengan in his One-Tailed form, and does not need to transform into his Three-Tailed form to use it. In addition, his One-Tailed form did not require the assistance of Shadow Clones.