you're clearly are bias...in that fight naruto too was handicapped since he came to fight while he was almost drained...heck even kakuzu said that naruto was a fool for fighting him when he was already beat up from the trainingKakazu was Fighting Kakashi Befor hand and kakashi Killed about Two of his Hearts.
Naruto Came in Close to the End of Their Fight, Kakazu wasn't 100%.
If naruto Fought Kakazu with All his Hearts and FUll chakra he would of demolished Base naruto.
and the reason naruto first FRS failed was bc it wasnt completed, if the frs was completed kakuzu would have died the first time naruto had attacked
and people stop w/ ur stupid plot no jutsu excuse...everything is plot in the manga...the reason kakuzu was that strong was bc of plot, so stop with your ridiculous excuses