Mid Kage level. Pushing his hype aside. He's very powerful given the right condition. Assuming his opponents are not oblivious they might counter his kunai that he uses to teleport with projectiles of his own. Then they mustn't have a way to destroy his kunais. They also have to let his distribute his kunai. Even after all those things top tier opponents must let him do, they must then be killed by either a rasengan or a Kunai. Based on cannon sources top tier opponents are not killed by kunais. Especially if they are actually in a heated battle and know they must pay attention to their surroundings. Given what we know of the current Kages, Tsunade's heavenly foot of pain could destroy the kunais that minato set or make then fall in the crevices created by her attack. Should he manage to attack her, the way in which rasengan works is it grinds against a person ripping apart their flesh over time. It is not a penetrative jutsu but a jutsu that relies on wearing down and weakening then ripping, and for that Reason Byakougou should be more than capable of healing from it. In addition to Tsunade is an evasion specialist. So I don't see her being caught by a Kunai so easily. For A where Minato needs teleportation speed A has footspeed and unless Minato hides a seal somewhere like he hid it on Bee A should be able to consistently react defensively to his teleportation and attack consistently. In addition I highly doubt that the Kunai is going the Lightning Armor V2 and I doubt the rasengan has enough penetrative or grinding power to reach A's flesh. Against Gaara, Gaara can sink the kunai's and cover any additional seals made with a decent amount of sand. If through some stroke of luck he manages to teleport behind Gaara, Gaara's Sand armor should be of help in addition to his automatic sand shield. And his ability to counter attack quickly. Against Mei, he'd probably win most of the time but she could wash away his kunais with large suitons or surround them with Lava release. Making teleporting to them work against Minato. IF she surrounds herself in acidic mist with no regenerative properties attack her head on will cause Minato to move slower and work against him. Theoretically throwing a kunai into the acidic mist should melt the kunai and destroy the seal. What works in his favor though against most of the aforemention kages is Gamabunta. With Gamabunta he'd probably would Beat A consistently and Mei. But Tsunade has kautsuyu to counter and she could probably kill Gamabunta herself. Gaara can probably kill Gamabunta with a stabbing sand attack unless Bunta uses his oil which would result in defeat for Gaara. Oonoki... defeats Minato pretty consistently. So I'm going to say Mid Kage level