So I did some math, and these are my results. No matter the timeline, the time that passes between generations is the same right?

RGBY/RSE/FRLG/ORAS
Red, Leaf: 11
Green: Unknown, but most possibly 11 too
Brendan, May: 12 (confirmed in ORAS)
Wally: 10 (confirmed in ORAS)

GSC/HGSS/DPPt (3 years have passed)
Red, Leaf, Green: 14
Brendan, May: 15
Wally: 13
Gold, Silver, Crystal, Lyra: Unknown, 11-12 possibly
Dawn, Lucas, Barry: Same as above

BW (Unknown time has passed)
Red, Leaf, Green: More than 14
Brendan, May: More than 15
Wally: More than 13
Gold, Silver, Crystal, Lyra: More than 11-12
Dawn, Lucas, Barry: Same as above
Hilbert, Hilda: 16 (confirmed)
Cheren, Bianca: 15-16
N: Estimated to be 20 years old (source: PASH! May 2013, Bulbapedia)

B2W2/XY: (2 years have passed)
Red, Leaf, Green: More than 16
Brendan, May: More than 17
Wally: More than 15
Gold, Silver, Crystal, Lyra: More than 13-14
Dawn, Lucas, Barry: Same as above
Hilbert, Hilda: 18
Cheren, Bianca: 17-18
N: 22
Nate/Rosa: Unknown, but they look younger than Hilbert/Hilda. Possibly 14
Calem/Serena: Emma is 16, and she says that she looks up to Calem/Serena as an older sibling. So 16 or more

Sun/Moon (unknown time has passed)
Sun, Moon: 11. Hau and Lillie probably are 11 too