What if the reason Giovanni is doing this is because when Necrozma opens all of the Ultra Wormholes one portal went to the past, back to when Ethan/Lyra defeated him in the Celebi event. As most of us know during this event Giovanni after being defeated leaves the cave you are in and a sound that sounds like a water splash plays. Most believe this to be him committing suicide. What if before he hit the water the Ultra wormhole opened underneath him sending through Ultra Space. Seeing all of the possibilities with Ultra Space he seeks out the Aether Foundation but before that he ventures through Ultra Space again to recruit Archie, Maxie, Cyrus, Ghetsis, and Lysandre from universes where they succeeded in their plans. Along the way he reencounters Mewtwo and finds a Mewtwonite Y and Key Stone. Eventually he captures the Aether Foundation and Festival Plaza because the AF is researching Ultra Space and the Ultra Beasts, and Festival Plaza because it's multidimensional power called Online Battles and Trading which gives him access to more dimensions incassable by Ultra Space (being other games).
