Cooperation Ninjutsu

Collaboration jutsu, also synchronized or combination jutsu, pertains to a branch of jutsu which entail powerful techniques that are actually comprised of at least two or more pre-existing jutsu. When initiated with the right timing, one will feed into each other to become a jutsu of greater power than the sum of its parts.

Although Synchronized Collaboration Jutsu has been seen used in the manga (such as the Fire Release: Toad Oil Flame Bullet technique), it was not explored much in the plot. In the anime, during the Three-Tails Arrival' filler arc, the concept of collaboration jutsu is more explored upon. As Jiraiya explained to Naruto Uzumaki, greater power can be brought forth by two ninjutsu users who combine two different elemental ninjutsu. This can either be in destructive power, range of the width and/or range of the attacks length. If two jutsu users cannot co-operate, then a collaboration jutsu is impossible.

Foundation
Collaboration jutsu is all about teamwork. Although collaboration jutsu can be used by ninja who can simply match each other's timing, the best results are seen when collaboration jutsu are implemented by users who are mutually like-minded and have a working understanding of each other's drives and character; the more time they spend together, then the more they can potentially become in sync with each other.

Ninja, such as Kiba Inuzuka and Akamaru, whose fighting style revolves around collaboration jutsu, are close friends and thus have a natural disposition for collaboration jutsu, as they can work together to execute a collaboration jutsu; as too do like-minded characters, such as Naruto Uzumaki and Gamatatsu, who mutually are both 'simple' and 'stupid'. Once a duo of ninja have reached an understanding and established a bond, they will be capable of working with collaboration jutsu.

Use
The most elementary application of a collaboration jutsu simply involves two users delivering the same technique at the same time (i.e. Kiba Inuzuka's and Akamaru's taijutsu: Dual Piercing Fang). This doubles the power of its predeceasing single-user technique, (i.e. Piercing Fang). This would be a two-way synchronized co-ordination collaboration jutsu.

Some collaboration techniques work because one element is weaker than the other element. However, there are also elements that possess a good affinity with each other. Wind Release and Water Release also have been seen as having a good affinity for each other in a collaboration jutsu. Naruto's and Yamato's Typhoon Water Vortex Technique is a wind and water combination that's created from the Wind Release: Rasengan and Water Release: Tearing Torrent. These would be examples of two-way synchronized elemental combination collaboration jutsu.