Durability is useless in this fight considering baku is suction power. Its also debateable whether Ao could escape from kotoamatsukami which is extremely essential to guarantee Ao's victory. If he uses a water wall and hides himself or maybe mist jutsu and blind the sharingan and then use a large scale water element jutsu to make danzo's footing incoherent and then apply genjutsu to capture him or use byakugan to see through the mist or sense him out given his top tier skills in sensing and use absorption to absorb his vacuum bullets and waves. All of this should happen before he brings baku. Baku literally makes ninjutsu other than fire useless and without a defense to block his suction power, every effort is meaning less. But if Ao can reverse absorb baku, and absorb his suction, then Ao wins, but I dont think baku suction is a ninjutsu, rather just pulling the wind inside him along with the capturing of spiritual things like Susanoo.