It's true believe it or not, it shouldNT be hard to believe really just match them up.
Naruto: he strength comes from Kyuubi and SM. These are power ups are all "other" chakra. He offensive kill moves are different rasengans and Tbb. I will explain why this is not the arsenal you wanna have when fighting Kisame.
Kisame: His offense is focus on stripping his opponent with chakra absorbing attack and man eating sharks and high levels of battle changing suiton. He has the the ability to absorb chakra naturally when in water and 6 tails worth of chakra through Samehada that he can you to heal from the worst injuries seen in the series.
Countering Naruto's Jutsu's Kisame has one of the highest chakra level and stamina in the whole show and can match Naruto's chakra even when he's using Kyuubi. Naruto's clone spam can be countered with his own clones, sharks, or even massive suiton jutsus. TBB is counter by the 1 jutsu perfectly designed to counter...Great shark bullet. If Naruto uses TBB Kisame would counter with GSM and absorb TBB to make GSM grow even more massive(it's already the size of the kyuubi; true fact) and it seem BM is a chakra manifestation of the Kyuubi that would probably get absorbed too which wouldn't even be need. If GSM make contact with Naruto
it will kill him
Countering SM and kyuubi chakra Kisame was the best in Akatsuki at capturing Jinjuuriki and for a reason. Thanks to Samehada and Kisame's chakra absorbing ability Kyuubi and SM chakra are eaten and not much use to Naruto. KCM which would vary between 1-8 tail worth of chakra. Kisame would absorb it in 1-2 swipes with Samehada and BM(9) would take 2 swipes. BSM would be 2 swipes as well, and for the one think SM would turn Kisame or samehada to stone read this
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Countering everything: else let's not fanboy be honest and logical it's clear as day and I didn't even mention Kisamehada fusion mode which absorbs chakra by just touching and can admit spike from it's body so If Naruto were to try his luck in Taijutsu it would not work. Water dome can also trap Naruto with no where to gone Water dome+ 500 sharks+ Kisamehada clones

Naruto only chance which is doubtful is to goes full BM which is countered in the above paragraph. Does anyone think Rasengan is enough to put Kisame down? I don't so even if Naruto somehow many to land a blow to Kisame I doesn't it killing him thanks to his healing ability.
I know deep down many people know this but would never admit it, Kisame is very underrated and should be acnowledged. I spoke my unbiased peace, it's up to you to acknowledge it.