>>18618349Generally, the events of all of the games released within a generation happen at about the same time. Black 2 and White 2 are the exception, which is clearly stated.
Furthermore, newer games can make older ones non-canon. Ruby and Sapphire are no longer canon because of the events of Emerald, for example, while FireRed and LeafGreen takes the place of all of the first-generation games in the series timeline.
It is very clearly established that Platinum takes place at about the same time as HeartGold/SoulSilver, thanks to the opening reports on the Red Gyarados at the Lake of Rage. HG/SS happen three years after FR/LG, and I would assume Emerald as well since Steven implies that he battled Brendan/May some time before you meet him in Kanto. The last Rocket grunt from HG/SS is known to have started a family in Unova by the time Black and White roll around. Finally, an NPC in X and Y mentions Team Plasma causing trouble a few years back, meaning that X and Y probably take place after B2/W2.
So we have FR/LG/E -(3 years)> Pt/HG/SS -> B/W -(2 years)> B2/W2 -> X/Y.
