Board Thread:Theories and Speculation/@comment-30168130-20161223235115/@comment-25122992-20161224184418

It just means that certain Buju have the elemental KKGs, and when a Jinchuriki uses their chakra, he can use their KKG nature thanks to it as well. Though Naruto has only the fragments of Biju chakra, it seems to be enough for him to use their KKG natures.