I say it was the Sasuke and Naruto big fight at the end of Part one. Then the sasuke fights in Part two. That led to what we got by the end.
In theory the three fight between the strongest characters in part one were Zabuza and Kakashi, Orochimaru and the Third, and Tsunade and Orochimaru. The first is suppose to shows us what a battle between two elite ninja looks like, the second is suppose to be a legendary battle that only Kage class ninja could fight at, the third fight is suppose to show us the strength of the new hokage, but all these fights look utterly tame compared to how the fight got to by the end.
Now I'm going to quickly go over most Naruto's fight and how they escalated.
Naruto v. Mizuki: Naruto tried out his shadow clones for the first time against and overly arrogant foe. He surprised his enemy into shock by summoning hundreds then just beat him up while he just stood there.
Team 7 v. Kakashi: Kakashi was a jonin while they weren't even genin yet. He played around with each of them, with only Sasuke surprising him by showing he could use an elemental jutsu. Which was more impressive to him then Naruto's shadow clones, despite we later learn Sasuke clan are experts at fire element techniques and learn them from an early age. You can already see where I may be going with this.
Naruto & Sasuke v. Haku: Haku was an prodigy that was and Anbu class ninja despite his young age. He trapped the two of them in a dome of ice where he would then slowly wear them down to exhaustion with a thousand cuts from his needles. He could have killed the two instantly at anytime but he had a soft heart, and simply want to keep them from interfering with his master battle and mission. This also hampered him since his dome was slowly draining him. Naruto made his goal to busted out by destroying the mirrors, while Sasuke notice Haku slowing down and decided to take pot shots at him. This quickly drained Haku and he realized he needed to knock them out starting with Naruto and then Sasuke. Then those two had an emotional moment, and Naruto activated Kurama's power. The two were outclassed the entire battle until Naruto activated his last resort power.
Naruto v. Kiba & Akamaru: Naruto had his power sealed by Orochimaru there by crippling him when he faces off against a two on one where all his classmates don't believe he stands a chance against his opponents. his opponents had a incredible sense of smell, fast, have pills that could increase their power, and a tag team technique that uses all their strengths in a flying drill move. He managed to defeat both by trickery by turning their enhance sense of smell against them.
Naruto v. Neji: Neji was a gifted prodigy from the villages most power clan and a year older then him. He also have all seeing telescopic eyes, a fighting style that target their opponents very ability to use their power, and a defensive technique that pushes all his enemies away. Naruto spends the fight trying to land a hit on him. Which he was final able to manage by tricking Neji into thinking he was knocked out while he dug underground to land an attack on him.
Naruto v. Gaara: There were two stages to this fight. One was the sand armor part the other the giant fight. For the Sand armor part Naruto quickly was able to think up a plan where he figured the weakest point of the armor would be the ass. So he spent alot of energy get an explosive there. Once he did and the armor was weakened he then ganged up on him with his clones and pummeled him. Then part two he summon a giant frog who explained to him his next objective. He needed to beat up gaara on top of the giant to him wake up which would weakness the giant.
Naruto v. Kabuto: Kabuto is a person that is consider to be on Kakashi's level, and was just able to hold his own against Tsunade who is soon going to be the next hokage. He is a medical ninja that uses his ability to harm instead of help. He was able to beat him able letting him attack him so he grab hold of him. Then use his new technique to defeat him.
Naruto v. Sasuke: Now then if you have notice a trend in all the fight I have brought up there are three things in each. One that was on a weight class above Naruto in someway. Two the had their ability shown and explained during the fight and their limitation after they were defeated. Three then once those abilities are shown Naruto has a objective of getting around those abilities in order to beat the guy up and generally used trickery that used either his opponents strengths and/or weaknesses against them. This fight it just showing off power with constant escalation, and Naruto goal isn't to beat Sasuke but to reason with Sasuke. Naruto uses shadow clones, Sasuke uses fire jutsu. Naruto uses the rasengan, Sasuke uses the chidori. Naruto is able to hold his own, Sasuke uses the curse seal. Naruto uses kurama's power, Sasuke unlocks his completed Sharingan. Naruto uses the chakra cloak, Sasuke uses curse seal level two.
Ultimately I believe the power level of the fights went off the scale because of Sasuke. Kishimoto for most of his characters is able to keep them grounded and show them competently in a fight even with the limits of their abilities. The problems is that one Sasuke is Naruto final opponent so his must always be stronger then him, two since we don't follow Sasuke on his journey we don't know how he got those power, their limitations or their growth, and since Sasuke has to keep up with Naruto but we don't see his growth eventually even when kishimoto does put limits on Sasuke abilities they have to be ignored so he can be a match for Naruto who in theory we have been following all this time. Also most of his fight were bull kitten.
Sasuke Part two fights
Sasuke v. Orochimaru: Orochimaru was sick and his body was already failing him when Sasuke betrayed him. Then was able to defeat him in a battle of wills. Allowing Sasuke to remain in control and gain a healing factor while Orochimaru went... somewhere?
Sasuke v. Deidara: Honestly this was Sasuke best fight in part two. He was able to defeat Deidara because his lighting cancelled out his earth bombs. Then the kitten that was the Snake shield happened at the end.
Sasuke v. Itachi: Genjutsu for the first half which Sasuke eventually won for some reason. Then skipping everything else to speed this up. Itachi ends up dying once he had won while he was throwing the fight the entire time.
Sasuke v. Killer Bee: Was his second best fight in part two. Bee lighting and sword play made him a match for Sasuke, and while Sasuke did have experience fighting a container before Killer bee was much more experience then Naruto. Then he threw the fight.
Sasuke v. The Four Kages. Sasuke despite his record so far of his enemies throwing their fights against him was somehow able to hold his own against the strongest ninjas in the world. By constantly pulling out new powers from his sharingan.
Sasuke v. Danzo: Despite Sasuke should be exhausted from his previous fight he is able to hold his own against Danzo. Thankfully Danzo used a technique in the fight that had an incredibly strict time limit.
Sasuke in the war arc: I'm trying to remember what he even did? Since he just stood around most of the time while other people fought.
Naruto v. Sasuke round two: More talking and more matching power for power with also power escalation. Naruto's Shadown Clones against Sasuke's fire techniques. Naruto's rasengan against Sasuke's lighting techniques. Naruto's power from Kurama against Sasuke increasingly overpowered Sharingin abilities.
All this led the Last move fight between Toneri and Naruto which was describe as Dragonball z lite. As well as Bolt fighting a god in his first fight.
Edit: For those that are wondering I think Naruto only had two real fights in part two. Naruto v. Kazaku and Naruto v. Pein.
Edited by Bail o' Lies, 27 February 2017 - 12:04 AM.