Hashirama was serious for like 2 seconds when asserting control over Tobirama, and in that short period of time, he managed to break free from Oro's restraint. Since it was his own brother who created Edo Tensei, chances are Hashirama ALSO knows the seals needed to break free.
However, Orochimaru has already confirmed that he doesn't mind letting them free on the battlefield against Madara, so we are definitely going to see the Hokage fight!!!
Note: the chakra-rousing was by both of them, seeing as Hashirama tells Tobirama he doesn't need to rouse his chakra, and you can see the chakra disruption when Hashirama says, "Tobirama". Also, the cracks on the floor suggest the epicentre is Hashirama.
However, Orochimaru has already confirmed that he doesn't mind letting them free on the battlefield against Madara, so we are definitely going to see the Hokage fight!!!
Note: the chakra-rousing was by both of them, seeing as Hashirama tells Tobirama he doesn't need to rouse his chakra, and you can see the chakra disruption when Hashirama says, "Tobirama". Also, the cracks on the floor suggest the epicentre is Hashirama.