>>718715232
Leaks explain things that are never explained in the game.

From the Flame and Earth Plate we know about the cosmic egg, the giants, and how Arceus Defeated them and made them into plates. the leaked pmyth5.2 "AUSU" directly explains this as well as the sinjoh sigil as to why dragonite, gyrados, and tyranitar were on there.
Because it the original myth, those pokemon came to being from the Winds(Dragonite) of Rayquaza, the Waves(gyrados) of Kyogre, and the Quakes(Tyranitar) of Groudon.

It also lays the groundwork for lore that was later reworks in Gen 6 as it talks about the Tree of Life infinitely growing (Xernas) and its roots draining all life from the land (Yveltal) and how the tree of life had to be cut down to make a hospitable land for pokemon and humans. As well as the war that is mentioned in Gen 6, but humanity was punished by Palkia and Dialga instead of the ultimate weapon.