>>712737550
Game Freak got hacked last year, among the leaks was discarded designs and lore. Things like interbreeding between Pokemon and people came up a few times, weird acts of violence, we got a more detailed outline on a possible cosmology, etc. Regis were meant to be remaining fragments of Arceus' birth that fought with it for some reason. Some of that might be referenced in the plates you can find in gen 4.