ORO is a key player ...

[Somnath Ghosh]

obito met with oro .then he get hashirama's cell from that tree.he get the body of madara which kaboto used in edo form.

 

[Stark]

No if Zetsu was Oro's experiment after Oro's death it would have been made clear if he defects from the Akatsuki or not, plus they never talk highly of Orochimaru.

 

[Dark Artist]

i always believe that Oro has a major part in this war

he is the smartest villian in naruto after all

smart enough to put hashirama' DNA in yamato

and alot of sharingan in Danzo hand

his scary LAB has alot of secrets remember the scroll that suigitsu found back then ?

his researches and informations helped Kabuto alot

he got even madara DNA

 

[Cassosphere]

I agree