>>30788524I don't know where Bulbapedia is getting this timeline for Sun and Moon. Just the other day, they had Red as "21", but soon after, it was "21-31". People seem to just be pulling numbers out of their ass without backing them up with concrete evidence. There's also the possibility that ORAS aren't concurrent with Generation I/III. With all the talk about other universes where Mega Evolution doesn't exist, it's reasonable enough to say that FRLG and RSE are concurrent, but ORAS is years later in a different universe.
Red's shirt says 96 and Porygon's Sun Pokédex entry says it was created approximately 20 years ago. You could argue that Sun and Moon take place 20 years after the Generation I/III of the non-Mega universe and 4 years after B2W2/XY/ORAS. Maybe ORAS takes place 2 years after XY since it came out in 2014 and XY were specifically stated to be concurrent to B2W2 which were released in 2012.
There are no official statements on the length of time between Gen II/IV and BW, or anything after XY though.