What we know for sure about Momoshiki Otsutsuki is that he heavily relies on his ability to seal, amplify, and release his opponent's jutsu when facing chakra-wielding opponents. The question is, despite that reliance, are there any justu he can use on his own? After all, Kaguya possessed a fair number.
Well, the literal answer is yes, we have seen him using one jutsu, that being Inukai Takeru no Mikoto, but even that is just a technique that utilizes the power of a Shinju.
So, what about when he created the fire pheasant and stone monkey to face Kurama? That is what my question boils down to: Do you think that these were techniques that Momoshiki could use by himself, or were they an example of him being able to manipulate the forces of nature within his own dimension like Kaguya could? Also, as a user of the Rinnegan, could he use each of the six realms?