The first piece was also Arceus and since all of the three pieces were shown to be three Arceus, that means the MC got "an" Arceus inside. The problem is: what power truly it has? The first one has the Archetype, but about the second one... I'm still blocked. Interceptor's power came from Adrest or it's completely independant? Let me explain:
We know that Adrest's soul was fused with MC in the first reset of the World, or it's almost sure it's a fact. But also we know that MC is just an entity from another world who was called by Variya to "substitute" "choosen MC" to be the Interceptor in their original body, revived by Crescent. In the Nightmare Realm, NPC MC told us they got 50% of Interceptor's powers, meaning the MC never shown their full potential, other than "not dying" or something. So...Adrest? What is his role inside MC? Is it possible that MC could be even more stronger than we could imagine after Ch. 15?
We only know that Ultra Beasts were important for Storm-9 and Xenpurgis, since it was said that this Rift Stakataka is the strongest Rift. Plus, Clear and Kieran both have Ultra Beasts and I don't think it's a coincidence.
No no no, it's a cool theory: somewhere, it was said that Yveltal is holding a Soul Stone when we battle it in Blacksteeple. It only has Decimation and no other moves, making him really weak to many strategies, but let's put that away, The point is: the Soul Stone can hold spirits who refused to die... the player could only capture Anathea's soul and she could be seen only in areas related to Vitus in the past. So...is it possible that Yveltal is holding a spirit? Or even Vitus' spirit, despite he was "fused" with Anju this whole time? Or even Yveltal is Vitus himself and he's holding someone as hostage?
About Giratina...it seems like I'm not the only one who thought it's impossible that Giratina was so easily fooled by some scientists and got captured. It's so strange that the first was in its Origin Form the whole time and the second only in the Altered form.
In the Third Layer it's possible to find notes about a woman named Lunala whose body rejected the Archetype and she got serious problems after that event. Casually, Melia pointed that Lunala is also the name of a Legendary Pokèmon. Then, there is the mysterious Mewtwo called Dranna, who was freed by Crescent from Madelis' control. Then, there is the strange Hoopa girl inside Aelita, and Vivian and Taelia too before her. Then there is Meloetta who seems like to be really important for the story. Then, Storm-9 is literally an altered Xerneas.
So...why we continue to see humans so related to Legendary Pokèmon that it seems like they turn into them? What is the meaning all of this?