1. Why do you have Kakuzu as stronger?
I just think Kakuzu is more versatile, Kisame is more of a matchup merchant than Kakuzu imo (he's someone who can tango with Bee but get stomped by Gai). Kakuzu has no weaknesses and can adapt to any fighting style. He's got everything covered at a high level. His gian cancelled out Kakashi's S ranked Lightning blade, and he can spam large scale elements like that casually, the scale of his attacks are absolutely massive. Look at the size of these trees compared to Hidan/Kakuzu [
x] , completely engulfed by his jutsu [
x ,
x]And he's virtually impossible to damage via physical attacks thanks to Domu, he came out of the two tails fight unscathed
From a portrayal perspective:
-The akatsuki 2 man cells are optimized to be impossible to defeat even for a tailed beast.
Hidan is underrated but he's no Itachi, Kakuzu has to do a lot of the heavy lifting for his cell for that claim to hold and the leader to have confidence that the group is just as effective as the others.
-Gai's rival was getting ragdolled by Kakuzu, while Gai was bullying Kisame throughout the series. Kakashi was also someone Itachi told Kisame not to mess with because he could give him problems [
1], and wanted to deal with himself resorting to his MS.