Madara cut himself to summon the mazo...

[Bansho Tenin]

so he has a real summing contract with it compared to obito and nagato who never did that to summon it....??????????????

 

[-ahhimane-]

That's how, he summoned it from the moon. Gedo is officially Madara's bit*h

 

[Henrik]

Didn't Obito summon Gedo mazo?

You must be registered for see images

 

[Bansho Tenin]

Didn't Obito summon Gedo mazo?

thats not what i meant you read it wrong.

 

[Henrik]

Oh. Well it was inside Obito, so he had to summon it. I think both Nagato and Obito would be able to do that, but might be wrong.

 

[Naruto.]

Right. The same way he tried to summon Kurama back then, but it had it's seal intact then. It was logical of him to cut his hand for that purpose.

 

[VongolaX]

They both used the black rod.

Remember Madara told Obito to use the black rod for ridukou technique and Gedo no Justu.

Madara used his rinnegan to break the seal of Gedo.

So basically, obito and Nagato have been riding on madara's will to summon Gedo.