Story wise i believe he fits better during the time right after the Kage Summit Arc and just before the War Arc when Obito and Kabuto joined forces, he wouldve been a creepy lab assistant for Obito all the while plotting his own plan of eradicating peace within the Shinobi World. His clones development would help further boost up Kabuto's Zetsu army and his constant research would help explain how he made the little Juubi clone (maybe through pieces of the Shinju Tree)
Thoughts?
Thoughts?