The theme that there's two games in a set. But you're the one who suggested that White might not be grouped with White 2 and that it's all based on color even though they abandoned that naming scheme after Gen 5, so if it makes you feel better to act condescending, go for it.
It looks like they're wearing Necrozma. His ability is Prism Armor. The clues were there all along.
If they do as they did with the Gen 1 VC versions, it means an easily obtainable Ho-Oh with Regenerator or Lugia with Multiscale.