3rd Raikage, more or less. If Raikage doesn't win, then at most, it's a draw for both. But I can't see Minato winning this one.
First, Naruto won because he had intel from the 8 tails. He was able to talk to him because he's a Jinchuuriki. Minato does not have that kind of relationship with any of the tailed beasts. I doubt he would ever figure out that the way to defeat Raikage is to have him pierce himself. Also, like someone said, Raikage does not need to use the "Ultimate Blade" to kill Minato. He's 2nd, 3rd, or even 4th strongest attack will do - and those may not be able to pierce his shield.
The only winning scenario for Minato is if Raikage does in fact USE the Ultimate Blade. But at the same time, he'd have to miraculously figure out to use that attack against Raikage. Out of the kages and countless jounin on the battle field, no one could figure it out? What makes anyone think Minato can? Plus, even if he did figure it out, FTG is not guaranteed to allow him a hit on Raikage. Raikage has some quick reflexes himself, and just popping up in front of him could be suicide.
Some people believe FTG allows Minato to be The Flash or something. Even if you can teleport behind someone, it still takes time to readjust to your settings. Moving from place to place so quickly, in my opinion, would almost create something similar to tunnel vision (ie. like that time Minato told Kakashi that Raikiri was an incomplete jutsu). And the fact that it doesn't necessarily increase your reflexes or allow you to see in "slow motion" leads me to believe that FTG may not conquer the 3rd Raikage.
So in the end, Raikage wins. Or it's a draw via Minato leaving the battlefield.
