Theres this video by The Game Theorists which is has a theory that in the timeline of the pokemon franchise, Pokemon GO is before Pokemon Gold,Blue and Red. It's pretty interesting and you should check it out
It also explains:
•Origins of Ditto
•Mystic and Instinct teaming up and having a war with Valor
•Why theres no teams in the pokemon franchise
•Professor Oak is someone else in the pokemon franchise
It's pretty interesting and I'd like to hear any thoughts about it