>>26740305So this is all pretty much untrue. The series takes place over a continuous range of time, not at two discrete periods. For example, we know from in-game dialogue that BW takes place after HGSS, but you have it as before. I think the timeline is usually considered to be something like the following (with remakes at the same time as the originals):
RBY/RSE -- GSC/DPP -- BW -- BW2 -- XY
I think there's been some suggestion that BW2 and XY take place simultaneously, but there's no in-game confirmation.