And Danzo is the leader of the ANBU so Minato knows most things about him. (probably not KA or the sharingans)I wanna say Minato would kill him before he activates Izanagi, but I'm not entirely sure, too many variables. By the way don't forget Danzo is the leader of Root, he knows everything there is to know about Minato.
I would say that the only thing that would give Danzo this battle is KA, but if he uses it on a clone then he is screwed. And before anyone screams about Minato not knowing how to make a clone, he did the multi shuriken jutsu, which is the same principle, except applied to a shuriken or kunai.
And if a kage can't make a clone then he would be a pretty terrible kage.