Honestly, looking at the current Edo Tensei I'd say it was Plot No jutsu he managed to seal them at all.
He fought the strongest ''mortal'' in Narutoverse and won. Hiruzen -WON-. He didn't lose. He sealed 3 Hokages ( including himself ) making it impossible ( until Kishi screwed it ) for them to be resurrected, while also disabling Orochimaru.
For an old guy that got ambushed and had no prep, that was pretty damn good.
But no, what he did was the max. attainable. Orochimaru stabbing him sealed the deal.
He fought the strongest ''mortal'' in Narutoverse and won. Hiruzen -WON-. He didn't lose. He sealed 3 Hokages ( including himself ) making it impossible ( until Kishi screwed it ) for them to be resurrected, while also disabling Orochimaru.
For an old guy that got ambushed and had no prep, that was pretty damn good.
But no, what he did was the max. attainable. Orochimaru stabbing him sealed the deal.