Zetsu is about as best as she is getting. Hidan Was capable of taking on Asuma, and the other 2 jonin. at once and Asuma would dice sakura up....Now if she had some good durability, then we'll be talking big kakuzu lvl characters. But nah.
Zetsu aside, I doubt she could beat any of the akatsuki without intel on them. Even with intel she'd only be able to defeat Hidan and possibly Sasori if she stockpiled antidotes. She'd probably still get funked up by the the Kazekage puppet.
Still waiting on someone from the akatsuki besides pain/obito/konan/kisame to do damage on this scale... Only then can I believe people who are saying she can only beat zetsu at max.
Sakura is so severely underrated it's hilarious. She's essentially Tsunade 2.0 and barely got into her stride. Sakura should be able to handle Zetsu, Hidan and Sasori with little difficult at this point.
She could take on Kakuzu at mid difficulty. She could take Konan w/ Katsuyu and no prep time for Konan. I'd even beter money on Sakura beating Kisame seeing as she uses purely taijutsu like Gai and she's easily stronger than 7 Gates Gai.