I think it's pretty cool that it's more or less confirmed that the "lost civilization" in Gen 3 was supposed to be Atlantis, and that not only was Metagross supposed to be an actual legendary but it and Latias/Latios were supposed to be connected to Groundon/Kyogre. The two evil teams were also fairly different but were turned into pretty much one generic team in two colors in the final game, looks like even back then Gamefreak had bigger plans they were never able to utilize. I can give or take the beta designs tho, they aren't very good.
These leaks have been very bountiful, we will be digging thru them for months if not years, and what is in them will work wonders within the ROMhack community(especially the official editors and source codes). If we can confirm the XYinsider alien theory correct, then I'm all set