>>58737101>>58737459Let's Go takes place in an altered Gen 1 timeline where Red/Green/Blue are all actually a few years older. All three of them have already completed their journey, but they did it before Team Rocket's activities were stopped by You and your bitchass rival. This lets Mina be around the same age as Red/Blue without completely fucking up the timeline. Not only that, but it (along with its young Mina) is just flat out not "canon" to the main timeline, because Mina obviously doesn't appear in RGBY/FRLG, and either RGBY or FRLG has to be the "canon" version of events over LGPE, due to Red and Blue's age and having defeated Team Rocket in Kanto.
The easiest way to "fix" the timeline is to not care, though. The distance between the games doesn't matter, and after Gen 4, all games except for remakes just take place after the previous one, with the exception of PLA because that's in the 1860s.
PLA > Gen 1/3 > Gen 2/4 > BW > B2W2 > XY > SM (USUM) > SwSh > SV > Z-A
Was that so hard?