Katakuri and the army are the main problems here.
Kisame defeat most fruit users via Suiton waves.
Deidera mostly, with the help of Sasori has to beat most of the fodder.
But those fodder are strong. And Akatsuki are specialist of 1 versus one, or 1 versus a few.
Big Mom is not a problem at all. There is plenty of way to beat her in a few second. A Genjutsu from Itachi can defeat her. Same thing with Kamui.
Smoothie and Cracker can't pass Kisame Waves. Cracker can escape Itachi Genjutsu but his skin is not as hard has his mother. One of the Akatsuki will localize him ( Zetsu ? ).
I don't know how they will beat Katakuri and the army.
Akatsuki has one shot jutsu and Suiton Waves but everybody as fast or as strong as Brook can be a problem for Akatsuki.
Amande can One-Shot Hidan, maybe even Kakuzu can fall in a few hits.
Oven can probably be a threat to Konan.
Globally. Deidera has to use C3 on the army fast or it could go either way.
With easily 2 dozens of Big Mom army on Jōnin strenght and speed, Akatsuki don't fear Big Mom, Cracker, Smoothie and the fruit users who can't pass the Suiton Waves and Genjutsu but Katakuri who can anticipate everything and an Army that strong.
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