>>38111006Anywhere between 6-10 years.
Most solid evidence is a Rocket from Gen 2 has a toddler (2-5 yrs) in Gen5.
So it's possible he had a girlfriend/wife and she got pregnant immediately, but more likely he moved back to unova, found a girl and within a few years got married and had a child with her.
So you have to make a LOT of assumptions, but it's reasonably speaking, 6 years or longer between Gen 2/4 and 5.