First of all there are techniques Minato has which we have not seen. Secondly, you guys are acting as if you don't read the manga, Minato's speed is fast enough to dodge the black flames and susanoo, though his only way (we know) to defend himself is his speed and has no known offense when attacking Sasuke, Sasuke will probably lose coz of Stamina. All Minato needs is one touch and the next time sasuke brings his defense down he will lose compared to Sasukes period of time to use Amatesru or his other attacks and sasuke's genjutsu is not powerful enough yet to take out Minato coz his genjutsu failed on A. Furthermore, all of sasukes attacks require him to prepare them, like the lightening attack and other moves while most of Minatos are instant. Also note that we are comparing a Ninja whose techniques we know to a Ninja whose techniques are vaguely known apart from his speed, teleportation and rasengan. I believe those who master the sharingan can only be defeated kage ranked ninja. The eye techniques in their arsenal can only be countered by a kage.