>>53225930>Pokémon Sun, Moon, Ultra Sun, and Ultra Moon take place 19 years after the Generation I core series gamesWhile that is one possible value, we can't definitively say how many years passed between DPPt/HGSS and BW. Based on established facts, we know the gap between Kanto and Alola must be between 10 and "roughly" 20 years, given that
>Anabel arrived in Alola as a faller 10 years ago, and she appears in Emerald>Porygon was invented roughly 20 years ago, and it appears in RBYWe likewise know the following canon timeskips
>RBY/RSE to DPPt/HGSS = 3 years>BW to B2W2 = 2 years>B2W2 to SM = 2 yearsFrom this we can infer that the gap between DPPt/HGSS and BW must be between 3 and 13 years. This is roughly correlated by the following:
>Caitlin is 14 in Pt and a grown woman in BW>The foreign Rocket grunt from HGSS has a young child in BWSo while Red could possibly be as old as 31 in SM, I think it's probably closer to the lower-middle of that range, which would make him about 25. It's no coincidence, in my opinion, that SM were the 25th anniversary of the series when it released