Ngl, all Naruto's teammates and even his SENSEI got a bigger buff. Sure, Naruto had to be taught the basics of being a ninja, since he wasn't even great at the basics in the 1st part (unless he was under duress.) but you're literally training under Jiriya, like come on, it can't take him all 3 years. I must credit Jiriya for opening the pathway for Naruto to master the 9-Tails' chakra. Other than that, I don't understand why Jiriya didn't teach Naruto what nature style he had, or at least teach him some fire jutsu. I wish Kishimoto didn't just completely leave Naruto in the dust.