Obito had the Rinnegan only for a short while before the War. Knowing the abilities doesn't guarantee that he can use any of them with the same skill level as say, Nagato, who had used the Path's abilities for many years, despite the power of his techniques being stronger due to having both an Uchiha body and Hashi DNA within that short period of time. Not to add to the fact that Obito didn't use any of the Paths offensively once ET was released, instead opting to use Kamui.
And Obito's statement against Gai and Kakashi in relation to his use of the Six Paths Techs isn't exactly 100% implicative of him being able to use all 6 of them. Of course he had the potential to learn them, however.
And Obito's statement against Gai and Kakashi in relation to his use of the Six Paths Techs isn't exactly 100% implicative of him being able to use all 6 of them. Of course he had the potential to learn them, however.