Cooperation Ninjutsu

Collaboration Jutsu, Synchronized Jutsu or Combination Jutsu pretains to an area of jutsu which entail techniques that are comprised of at least two or more jutsu that, 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, it was not explored much in the plot. In the anime, during the anime-only 'Three-Tails Arrival' filler arc, collaboration jutsu is explored more. As Jiraiya explained to Naruto; greater attack power can be brought forth by two ninjutsu users combining two different elemental ninjutsu in combination, either in destructive power, range of the width and/or range of the attacks length. The rest of the arc includes Naruto's progress with collaboration jutsu with Gamatatsu and Gamakichi.

Foundation of collaboration jutsu
The foundation behind all collaboration jutsu is that two or more ninjutsu users need to be able to understand and get along with each other in order to be able to impliment a collaboration jutsu. This is emphasized to Naruto in the 'Three-Tails Arrival' arc by Jiraiya and by Gamakichi.

Types of synchronized 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,) to double the power behind it's predecessing single-user technique, (i.e. Piercing Fang.)

Another interpretation of a collaboration jutsu is one that needs a group of people in formation to engage, (i.e. Four Violet Flames Battle Encampment or Four-Corner Sealing Barrier.)

Some collaboration ninjutsu work because of the Ninjutsu elemental cycle: It has been demonstrated that in the instance of Fire Release and Wind Release collaboration ninjutsu; that when two ninjutsu users use their techniques with the right timing, the wind-natured chakra of a wind release ninjutsu will feed into and increase the power of the fire-natured chakra making the fire release ninjutsu much more destructive and dangerous to the target. It has yet to be confirmed or disproved whenever-or-not Fire-natured chakra could strengthen a Water-natured ninjutsu, (considering that, according to the elemental cycle, wind strengthens fire).

A sufficiently experienced and powerful ninja on his/her own may be able to execute two different elemental chakra natured ninjutsu with the right timing to combine into a collaboration technique more powerful than the two techniques that made it. This was demonstrated with the Earth Release: Earth Dragon Bullet technique and the Fire Release: Fire Dragon Missile technique, used by Hiruzen Sarutobi during his fight against Orochimaru in the 'Invasion of Konoha' arc.

Aside from collaboration techniques that work because one element is weaker than the element that came before it clockwise, their are also elements that possess a good affinity with each other. These 'good affinities' seem to appear in elements that are found on either side of an element that one would naturally be strong against and the other would naturally be weak against, (i.e. wind and water (either side of fire), or fire and earth (either side of water).)

As demonstrated in the anime by Hiruzen Sarutobi, Fire Release has a good affinity with Earth Release and can be used together to become a collaboration jutsu. The Fire ninjutsu needs to be implemented with the right timing in order to combine with the Earth ninjutsu, the Fire chakra being provided with more solid force and more explosive force from the Earth ninjutsu. It noteworthy to comment that both fire and earth are on either side of water.

Wind Release and Water Release also have seen as having a good affinity for each other in collaboration jutsu. The manga and the anime both show Naruto Uzumaki's and Captain Yamato's Typhoon Water Vortex Technique, a wind/water collaboration jutsu, countering Kakuzu's masked monster heart creatures unnamed Wind and Fire Blast Technique. The next arc, the 'Three-Tails Arrival' filler arc, includes the creation of the Wind Release: Toad Gun, and then the Wind Release: Toad Oil Flame Bullet, (substituting Toad Oil for water,) used to overcome a water creature and evaporate the water.

While a Fire Release technique is usualy weak against a Water Release technique of the same rank, a wind/fire collaboration jutsu is effective against a Water Release jutsu, as seen by Kakuzu's unnamed Wind and Fire Blast Technique overwhelming Kakashi Hatake's Water Release: Water Encampment Wall defense. Meanwhile, in the case of a wind/fire combo versus a wind/water combo, the two, when they hit each other, will cancel each other out. It noteworthy to comment that both water and wind are on either side of fire.

It seems that Lightning Release and Water Release can also be used in a collaboration jutsu; hinted in the anime, in Part II's ep 85, during Shikamaru Nara's fight against Kakuzu, (before Shikamaru forced Hidan away onto the Nara clan's land,) Shikamaru used Water Release: Water Field to turn Kakuzu's Lightning mask's Lightning Release attack against Kakuzu before he could kill Choji Akimichi and Ino Yamanaka. It noteworthy to comment that both water and lightning are on either side of earth.

Two-way collaboration jutsu, like the Fire Release: Toad Oil Flame Bullet technique and the Wind Release: Toad Gun technique, have made appearences in both the manga and the anime, and are usualy resposible for turning the tide in battle. Three-way collaboration jutsu, like the Wind Release: Toad Oil Flame Bullet technique and the Sage Art: Goemon technique, are jutsu of such power that they have so far only been seen used by some of the most powerful ninja in the whole series. Aside from Naruto in the 'Hidan and Kakuzu' arc and the anime-only 'Three-Tails Arrival' arc, collaboration jutsu has not yet been seen used by anyone below Jonin rank.

Speculation
Seeing that certain elements have good affinities with others, it has yet to be revealed how many other two-way collaboration jutsu will, at least in the anime, make an appearence:
 * Fire Release and Lightning Release combos
 * Earth Release and Fire Release combos
 * Wind Release and Earth Release combos

Also See

 * Dual Piercing Fang - Kiba Inuzuka with Akamaru; Inuzuka clan Hiden Jutsu
 * Combination Transformation - Naruto Uzumaki with Gamabunta
 * Four Violet Flames Battle Encampment - Sound Four
 * Earth Release: Earth Dragon Bullet & Fire Release: Fire Dragon Missile - Hiruzen Sarutobi (Third Hokage)
 * Fire Release: Toad Oil Flame Bullet - Jiraiya (or Naruto Uzumaki) with Gamabunta
 * Man Beast Combination Transformation: Double-Headed Wolf - Kiba Inuzuka with Akamaru; Inuzuka clan Hiden Jutsu
 * Dual Wolf Fang - Kiba Inuzuka with Akamaru; Inuzuka clan Hiden Jutsu
 * Wind and Fire Blast Technique - Kakuzu's Wind and Fire masked creature
 * Typhoon Water Vortex Technique - Naruto Uzumaki with Captain Yamato
 * Water Release: Water Pistol - Jiraiya with Gamariki
 * Wind Release: Toad Gun - Naruto Uzumaki with Gamatatsu
 * Four-Corner Sealing Barrier - Shizune with Sakura Haruno, Hinata Hyuga, and Ino Yamanaka
 * Wind Release: Toad Oil Bullet - Naruto Uzumaki with Gamatatsu
 * Wind Release: Toad Oil Flame Bullet - Naruto Uzumaki with Gamatatsu and Gamakichi
 * Sage Art: Goemon - Jiraiya with Shima and Fukasaku