I'm now going to respond to the supposed "debunks" of these characters scaling to the biju.
I've already shown why sakura's AP does not scale to sasori, so unless you actually have an argument as to why she does, you cannot claim she does.
Now for starters, the entire akatsuki is not being upgraded to 6C as some of them are already placed at biju level in tier or simply fo not have any feats of being biju level, such as Hidan. Not everyone the akatsuki fights scale to them. For example sasori vs Sakura and chiyo. Niether chiyo or Sakura scale to sasori's ap And niether of them are capable of tanking his attacks. Another example is base naruto and kakuzu. Kakuzu literally blitzed naruto and would've killed him had it not been for the intervention of Yamato and Kakashi. It is directly shown that kakuzu was tricked by naruto's shadow clones as well and was attacked from his backside, where he was off guard. Naruto also never tanks any of kakuzu's attacks, and the only reason he was able to hurt kakuzu was due to the Rasenshuriken bypassing conventional durability as it cuts on a cellular level. The 9 tails tanking this is completely irrelevant as well considering the fact the 9 tails is significantly above every other biju anyway.
The Rasenshuriken does not possess the AP to hurt kakuzu, it just bypasses his durability, so the shinra tensei dissipating it would be irrelevant in the context of kakuzu's durability. And even if you did argue that the shinra tensei is stronger than kakuzu's durability somehow, that would just mean 6 tails naruto is stronger than the normal biju, which would also be uncontested by anti-feats as that is his only feats.
Hashirama witnessed both Tsunade and Sakura fighting during the war, and it was ksihimoto's intention to make Sakura surpass Tsunade or he wouldn't of included the statement. So yes hashirama is still valid here.
No the biju did not randomly get stronger in naruto. Gamabunta was hurt by shukaku, and was only able to hurt a suppressed shukaku and never actually defeated him by conventional means as naruto was required to hurt gaara in order to beat Shukaku.
No chiyo's puppets cannot beat biju as they don't scale to anyone who is biju level, I've already explained why beginning of part 2 Sakura wouldn't scale to sasori so no again, and by scale to sasori I'm obviously referring to his AP with his iron sand and 3rd kazekage puppet his puppets durability is irrelevant as there is no way to scale it to biju level.
The sasuke that fought Sick Itachi was weaker than MS sasuke, and that itachi was holding back and was extremely weakened due to sickness.
Kurama is stronger than all of the other biju therefore the most significant portion of the 10 tails and then you combine this with naruto's power in their kcm 2 form. It would be perfectly reasonable for him to scale to the 10 tails as Kurama alone is the most significant portion of the 10 tails, excluding the amp that naruto gives him. Once again no anti-feats, this is just a perpetual argument of absurdity, which is dishonest and fallacious.
There is no speculation that kakuzu tanked that attack from the 2 tails, and I've already explained why it is likely for kakuzu to be the one to hurt the 2 tails but I've thought of a new argument as well. If his earthstyle is capable of withstanding the force of a biju he should logically be able to output that much force as well, this is basically a reversal of the counterforce of an attack which allows that person's durability to scale to their AP as well. The fact that kakuzu can manipulate his earthstyle to be durable enough to tank attacks from the 2 tails, he should have that same ability to convert that energy into an attack as well. This is supported by the fact that everyone of kakuzu's abilities are AP based and the akatsuki chose members capable of dealing with biju, so the akatsuki wouldn't of hired him if his AP wasn't capable of damaging him. This is consistent with the data book statement about the akatsuki being stronger than the biju. These are multiple reasons as to why kakuzu likely has the AP to hurt a biju.
No the discussion of whether the biju are 6C is irrelevant because this thread's focus is not upon the true AP of the biju but rather the scaling of the characters to the biju.
You keep saying that this upgrade would break the scaling because of how many people scale to the kage and the akatsuki, but so far every character that has been brought up either doesn't scale to these characters or do scale to these characters and should also be upgraded, you cannot say that the downfall of my arguments is that's I am ignoring the exterior characters affected by the upgrade, if I have addressed every character affected by the upgrade lol.
In actuality there aren't that many characters that scale to the ones listed anyway, so yes the biju would still be high in the verse.
Now go ahead and continue trying to find counter arguments, I'll gladly continue.