>>44287668It's actually exactly because of Cyrus in USUM and Generations that I think Dialga and Palkia do not have omnipotence. Rather, I believe Team Galactic misjudged DIalga's and Palkia's powers, similar to how team Magma and Aqua misjudge Groudon's and Kyogre. I'll try to lay out my thinking.
At the moment of his success, Cyrus is taken by Giratina to the distortion world. Once there, he realizes this is his perfect world, a world without spirit. It's a bit of a Monkey's Paw wish, you see. With the power of the creation trio, he could obtain his perfect world, but it wasn't by creating a new galaxy. In USUM as well, he clearly doesn't know exactly what is going on. The perfect world that he returns to is likely simply the distortion world, since Cyrus was transported by Giratina in the first place.
It might seem like a reach to say that Cyrus simply misjudged the creation trio, but think about it. All they go off of is myths and legends, like Cynthia, and they clearly did not really know what they were doing, as Cyrus had no idea what Giratina was.
If we consider the feats of the mons as well, this lines up here too. The mons never show feats that would require omnipotence.
We also have to consider that in all incarnations, anime, manga and games, the trio can be beaten down just by hitting them really hard, like any pokemon, which is once again not very omnipotent cash money.
Basically, what I'm saying is that virtually nothing in the lore says that the creation trio actually have divine powers, except the words of unreliable in-universe characters, and ambiguous official communications.
(For one, "With the beginnings of a new universe" could simply refer to the distortion world, which would be a new universe to team Galactic).