Oh I wasn't discussing about him being able to solo the entire war, that is a little too ludicrous. I was just trying to discuss about the sealing art.
And he has only shown four techniques that are fuuinjutsu related: "Flying Thunder God Seal", "RDS", "Contract Seal", and "Eight Trigram". I seriously doubt that is the only thing he has in his arsenal after all the evidence on how Uzumaki were amazing on sealing techniques. There is even evidence that Minato would have been able to make a gigantic barrier to keep Kurama from escaping, though he has interrumpted by Kushina who took charge on that task.
Minato hasn't had that much screen time, but is very unlikely that the only technique that he has to seal things is "RDS". If you see what is going on in the manga, no one has been capable of sealing any Edo "permanently", but use a "space-time blocker" with that Tag they put after binding them with either cloth or sand. I just feel Minato would be capable of creating such tag with his expertise on fuuinjutsu. If not, then his entire training with the Uzumaki was pretty much lame.