Board Thread:Naruto Discussions/@comment-27829630-20151231135502/@comment-25122992-20151231140521

Just because Gedo Statue got some chakra from both Kurama (Kin/Gin brothers sealed inside treasures, who possessed his chakra) and Gyūki (tentacle which Killer B left to escape from being captured by Sasuke, it also contained a bit of his chakra). The entire Tailed Beast wasn't nessessary for Juubi's revival, a bit of their chakra proved to be enough, although due to this Obito's Ten-Tails was considered to be incomplete.