The impact from the explosion causes the Third Raikage to close his eyes and his eye lids should be durable enough to tank a water bullet. Then the 3rd Raikage puts on his lightning armour again.
Minato can obviously dodge amaterasu. That was just a joke signature to remind me of the thread where a poorly constructed runon sentence caused a massive shitstorm lasting 33 pages.
The Third Raikage is too simple of a fighter and will be constantly trolled by the Mizukage so it isn't a low diff win when Raikage only wins by outlasting him. On the other hand, I don't see Ay winning this at all, let alone with low difficulty.