>>46619882In SM, Anabel is noted as having fallen through an Ultra Wormhole 10 years prior to her appearance in SM, Emerald is parallel to the Kanto Games in the timeline. That's where the lower limit comes from, as for the upper limit, that comes from Porygon's SMUSUM dex entries which state it was created 20 years ago and since it appears in Gen I that means that the games take place no more than 20 years apart. I'm pretty sure though that it's supposed to just be 10 years though since Anabel's is more of a concrete period of time where's Porygon's is merely an anchor for a limit on how far back Kanto was.
