Minato high diff.
-Minato showed he can mark a battlefield that is far larger than covering size of Juubi and Shinsuusenju. He can cover all the battlefield with FTG kunai. This would essentially make all of use Hashirama's techniques useless.
-Flower tree world gets avoided by FTG, and the focusing pollen area gets one shotted with TBB. Jukai Kutan would be destroyed by Giant rasengan. Wood dragon if restrained Minato, then he can easily teleport out of it as he did to Kamui, or he can one shotted with TBB as Kurama did. Mokujin if catches a TBB and tries to throw it back at Minato, then he can perform multiple TBB to destroy it.
-Hashirama will enter Sage mode throwing sealing gates, but Minato teleports out of it. If the Shinsuusenju has been summoned, and Hashirama using its powerful punches, it will be rendered useless. Minato as shown in the manga, can mark a bigger battlefield than the covering size of Juubi and Shinsuusenju. Just to note, V3 Juubi is bigger than statue according to the calculations DemonicAvenger and T Bogard done. Meaning Minato can teleport out of where Shinsuusenju aiming to punch to a safe place. He can charge a massive TBB. As he did against Obito, and throw it back at Staute destroying completely. Statue hasn't shown any feat of reaction or speed that allows us to say he can reflect massive TBB attacking from behind.
-Taijutsu is useless against Minato as a simple touch from him can leave a mark, and Rasengan to the back. That is if Hashirama try's to fight him physical combat.
With all of Hashirama's techniques countered and he is left powerless against the versatility and powerhouse Minato possess, gets one shotted with Shunshin. Also, Hashirama doesn't have larger chakra than Kyuubi as feats don't show this nor hype. Minato besides Obito, is Hashirama's opponent, and he beats him.