>>41067391RS were the only games there you couldn't use all the mons from the start but they all were coded in and when FRLG were released you could play all the pokemon in them. All the other ones you could transfer all the pokemon from older games to them almost immediatly except XY because pokebanks took a few months to work.
This is literally impossible in SwSh because many of the pokemon aren't even coded into the games, hence erased.
