There is no rule about them being balanced per team lol. That's headcanon, they were looking for replacements for Orochimaru and found Deidara, who is in no way equal to Orochimaru. That team is immediately signifciantly weaker than before.
Hidan was only paired with Kakuzu because he couldn't die, etc.
Their entire dynamic is functioning teams that can capture a Jinchuuriki, not that each team has to roughly equal the same level. That's a you invention.
Kakashi was stronger than Kakuzu. If Naruto didn't show up, he's confident he'd be in the hospital for using Kamui. So he's 100% confident he's beating Kakuzu.
Hidan was only paired with Kakuzu because he couldn't die, etc.
Their entire dynamic is functioning teams that can capture a Jinchuuriki, not that each team has to roughly equal the same level. That's a you invention.

Kakashi was stronger than Kakuzu. If Naruto didn't show up, he's confident he'd be in the hospital for using Kamui. So he's 100% confident he's beating Kakuzu.
Itachi told Kisame to sit tf down or Kakashi will hurt him. Kishi never presented Kakashi as even on Kakuzu's lvl. Kakashi was immediately portrayed on Kisame's level the first time they interacted. Gai proved it too.
And again, there is a pattern with the cells no matter how much you deny it. They aren't giving Itachi someone they think is stronger than Kakuzu or Sasori. And leave the other cells short. Nor is Kishi doing that, it would be smarter to let Kisame lead a cell if he was him.