>>54348031There's at least 20 years between Red and Green to Sun and Moon
Source? Red's shirt saying 96 as a reference to the release of RG, the early concept stuff they made for the series, while not canon, bits and pieces of its lore are still included into the series to this day, and they state Porygon was made pretty close to the year RG were made, implying RGBY take place in 96, this is double down on with Porygon's pokedex entry in SM saying its been around for 20 years
Seeing as Leaf/Green is Red's counterpart, its stated Red is 11 during the events of the Kanto games, it can be assumed she's the same age as him, making her somewhere around 31 by SM
As an added bonus, GSC are said to take place 3 years after RGBY, implying it takes place in 1999, the same year Gold and Silver came out, BW to B2W2 is a 2 year gap, just like their real world releases
The only games that wouldn't be around when they were released are the games meant to take place around the same time as other games. FRLG and RSE, HGSS and DPPt, B2W2 and XY (originally), and prequel games like PLA, but they referenced how much time had passed between it and DP via the protag's age of 15