Yeah..... to me the biggest plot hole in this is explaining how Kakashi got that much power from Obito. More than Obito had for himself.
I can easily believe Kakashi got Rikudou's power though, because Obito did have them. That black staff, the Rinnegan, the Gudodama - those are all powers of the Sage of Six Paths (aka Rikudou). The place where we see Indra and Asura's chakra merge is in the Rinnengan, which was made from Madara and Hashirama, who possess/are the chakra of Ashura and Indra.
If you think about it, when Obito was giving the dying Naruto his leftover percentage of the Tailed Beasts, that also coincides with the moment that Naruto awakened/saw Hagoromo in his psyche. Doesn't that indicate that upon Obito transferring his chakra to Naruto, Naruto was able to become a pseudo-Sage of Six Paths? Because otherwise, why did Hagoromo wait until that long to appear? I don't think he could have given Naruto his power if Naruto didn't already possess a portion of all of the tailed beasts. So that's why he appeared at that moment.
That hypothesis would settle Obito's ability to give sage-of-six-paths-chakra to others, but the whole point was he didn't have much of anything left! And Hagoromo said he'd given away his chakra too, so Kakashi couldn't have gotten it from him. It's a legitimate plot hole..... :erm:
= aliens