i see no problem in make the first game with only 151(and a few more, including their evolution, megas, and 6th general mechanics) pokemon.
Make red/blue (re)remake, but the way we want.(as described in this tread)
2 years latter make the gold/silver (re)remake, as and adictive game(all kanto is there, you can restart a new jorney in johto, and after finishing, you get what you had in kanto).
2 years later, ruby/saphire, 2 year DP, more 2 year BW and XY.







