hokages 1-4 are sealed inside of the Death Gods stomach. 1-3 when hiruzen and orochimaru fought he sealed himself and the other two. Minato used the reaper death seal and was sealed in the death gods stomach against kurama and obito. theres no dna of the SO6P. Jiraiyas body was too deep under water for him to get dna
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hashirama, tobirama, hiruzen, and minato's souls are sealed in the reaper death seal, therefore they cannot be summoned, I'd imagine SO6P's dna would be next to impossible to find, and even if he did, madara escaped edo tensai so so6p most likely could too, and jiraiyas body is deep in the ocean so in conclusion YOU'RE a dumbass. pay attention.
He needs to find SO6P's DNA.
And he used Hashirama's DNA to give Madara some powers and a face on his chest.
Minato's soul is in the sealing jutsu thing, I don't think it would work.
Jiraiya's body is underwater, he can't get it out to get the DNA.
When he performed the edo-tensei he explained why he couldnt summon Hokages 1-4. He has also explained why he couldn't summon Jiraiya and so6p DNA couldn't be found. Kabuto already explains this in the series and manga.