Spoiler: (highlight to view)
So I was thinking about how Cosmog looks really similar to Lunala. What if Cosmog is like the Zygarde core in a way and it has to gain more power to get to Lunala's form and when it's weakened it turns back to this little galaxy ball. I guess the same goes for Solgaleo but the "pokemon" that was next to Solgaleo in the datamine looked really odd.. And it doesn't really look like a pokemon to me lol. Also with Lunala being an emissary of the moon and Solgaleo being an emissary of the sun, that just makes Zygarde complete form the emissary of the Earth? I am like 90% they may be connected or have similarities