This is before we think about the Mystery Dungeon and Ranger series and then there's Let's Go which muddies the waters with putting Alolans and Mega Evolution into Gen1
Yep, it's a mess with wormholes and multiverses.
This is the best timeline i've seen
The top line of games are correct due to Pokemon Company confirmation but the rest is (decent) theory based on in game evidence.
Believe it or not, Pokemon DOES have a timeline, like Zelda it potentially even has a split timeline thanks to Mega Evolution and the games don't go in order of release.
For example Gens 1 and 3 happen at the same time whereas Gens 2 and 4 happen at the same time a few years later.
But do you...