>>22012633Zianna's thing implies multiple universe theory though, with an infinite number of universes and an infinite number of Rayauazas.
Groudon and Kyogre in HG/SS are three years after the events of R/S anyway. There's no reason they couldn't have migrated there after the credit roll. It's technically not canon to catch them.
The only canon catches by protagonists are BW/BW2 and maybe Rayquaza and XY.