Pokemon, what happened to you?

[Chaoxys]

From what I can tell, gen 1,3,and 4 take place around the same time while gen 2 takes place 3 years later (If I remember correctly, Red's mom says he left 3 years ago after becoming champion or something). Since you can trade between FR/LG with R/S/E, I'd assume they are in the same time period, and I'd say 4 must be close as well.