OK, so here is what I have tried to catch so far
Pokemon Red run is undoubtly the first one that happened.
Pokemno Crystal happens 3 years after Red run.
We know that Emerald to Heart Gold happen after those, but the time between is unknown (Just knowing that Heartgold run happens 3 years after Fire Red)
Then, we have Pokemon Black, who, again, happens after an unknown set of time.
Pokemon Black 2 happens after these games, 2 years after pokemon black to be exact, but some time before others (due to the hosts having been teleported from the past more likely than from the future)
Pokemon Anniversary Crystal and Anniversary Red happens after these as well, but once again, the amount of time is unknown, all we know is that its enough to have AJ be still quite young.