to those saying he cant absorb susanoo, yes he can. he can absorb it the same way he absorbed an eight tails cloak in an instant to become young in chapter 550. and judging by the speed he absorbed that, i wouldnt take long for him to absorb perfect susanoo.
could madara counter him before he can completely absorb perfect susanoo? the moment he starts absrobing perfect susanoo it wont be perfect susanoo anymore, because like we say with bees eight tails cloak when sameheda absorbed it, those chackra cloacks which yes susanoo does fall under go into a much lower form even if they arent absorbed in an instant, which i think would be madaras only ability to counter chackra absorption even when starting in perfect susanoo, but then nagato could just dodge the smaller susanoo weapon and absorb again to finish the job.
if a tailed beast cloak is chackra based then so is susanoo. they are basically the same thing which is chackra in physical form. and amaterasu is also made out of chakra as it is a ninjutsu which is why it was countered by omyouton