I just have to say, in Su/Mo Necrozma felt awkward, out of place, and felt as though it was intended to be way more than what it ended up being in these games. I really am happy with all of the care, respect and development of this Pokemon. Necrozma actually appears to be a threatening and dangerous pokemon that possibly even eclipses the threatening presence that Mewtwo has provided all these years. Necrozma feels like the first really well developed antagonist Pokemon that actually provides a significant amount of danger to the Pokemon world. Most of the Legendary Pokemon are just out of control or acting out of their natural instincts. Necrozma however is actively a threatening presence that seems to understand that what it is doing will most likely destroy the world that Alola is located in.
I just think Game Freak took an awesome direction with Necrozma and because of the direction the story seems to be going in for USM, it has really fleshed out Necrozma as a seriously terrifying Pokemon with incredible world destroying powers and it doesn't seem to have any empathy towards the world that it is in the process of destroying. Very cool Pokemon, might end up being one of my new favorite Legendary Pokemon.