Minato always throws out his kunai at the beginning of a fight, so that he has options.
however, especially under the conditions set by the op, kisame is no piece of cake. i would be very surprised if one rasengan is all it takes to defeat him, he's shown naruto levels of durability and stamina. it was his bad luck that he came up against a pure taijutsu user, that shark technique of his which was defeated by afternoon tiger was beastly otherwise, it would defeat pretty much anyone's jutsu.
yes he will get marked pretty early, but even if he gets hit he can merge with samehada and enter that water dome he makes no at least partially negate minato's superior speed and reflexes even when he teleports on top of him. minato wins, but he will have to work for it.