Hashirama cells, Shisui's MS and it's genjutsu and other attributes, futons, seals and summon are enough
If those factors would be enough against Ay, Danzo would just dogwalk Sasuke, he didn't. He couldn't.
Let's be honest, Danzo would have had far more chakra during that fight if he was utilizing his body + 3T to evade attacks rather than using very chakra consuming izanagis.
Bruh, he's not evading attacks from someone who can even blitz Sasuke in V1, let alone V2 when even Amaterasu was too slow. Sasuke couldn't even follow this guy.
At least with Izanagi, people could argue Danzo would use this opportunity for a successful sneak attack considering he has some hax jutsus as well. But without it? No chance. Even then, Ay's reflexes are crazy good and in cases of surprise attacks, his armor is a great defence.
same futons that broke through Susanoo?
even armored bow susanoo needed to use a shield
You mean these panels?
Sorry but his summoning beast was already affecting Susannoo quite a bit while Danzo dealt this negligible damage to Susanoo's back - which iirc is a more vulnerable spot.
While he was trying to attack it even further, Sasuke used Katon jutsu on the beast and then did this:
I've also re-read the fight and it's crazy how Danzo could not even dodge a SINGLE Susanoo arrow. The first one was stopped due to Danzo forcefully releasing his Hashirama cells to create a tree redirecting the arrow. In all other instances, Danzo died over and over again.
Idk if this was because Danzo was being "careless" or whether he was genuinely not able to dodge these. I think, without Izanagi, Danzo wouldn't fight Sasuke as careless but we've seen several times that Danzo struggled to even keep up with Sasuke.
Furthermore, Danzo specifically wanted to stall this battle cuz he knew Sasuke can't always spam his MS techniques because he'd become blind and too weakened afterwards. Against Ay, he cannot maintain the same strategy, Ay's chakra was compared to a Biju.
I think Danzo (without Izanagi) would have it easier killing Mei but Ay is a different kind of beast.