Red - Early 2018 (skip all moon trainers)
Yellow - Early 2020 (Ice beam)
Gold - Early 2018 (Manip)
Crystal - Mid 2018 (Raikou)
Sapphire - Early 2021 (Abra)
FRLG - Early 2016 (Exarion)
Emerald - 2018 (Abra)
DP - Mid 2016 (Lucky egg)
Platinum - Early 2016 (Kricketot & Pokerus manip for Piplup) or Late 2020 (Chimchar)
HGSS - Late 2018 (Voltorb flip)
Black - Early 2020 (Lillipup)
White 2 - Mid 2016 (Drilbur manip)

Oldest to Newest:
Platinum - Early 2016 (Kricketot & Pokerus manip for Piplup)
FRLG - Early 2016 (Exarion)
DP - Mid 2016 (Lucky egg)
White 2 - Mid 2016 (Drilbur manip)
Red - Early 2018 (skip all moon trainers)
Gold - Early 2018 (Manip)
Crystal - Mid 2018 (Raikou)
Emerald - 2018 (Abra)
HGSS - Late 2018 (Voltorb flip)
Yellow - Early 2020 (Ice beam)
Black - Early 2020 (Lillipup)
Platinum - Late 2020 (Chimchar)
Sapphire - Early 2021 (Abra)