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On the other hand, this would be the first time since the Kanto games where your opponent for the Champion spot is your rival (well besides the Title defense battles in SM). It might be just me but I liked the idea of your final battle being your rival from the very beginning and having raised...
So in the scope of the Pokemon multiverse, can we say that the event that diverges the SM universe from the USUM universe is that Necrozma did not steal the light of Ultra Megalopolis, and thus the Ultra Recon Squad never arrived in Alola, in the SM universe?