>>57579003Not including a large number of Pokémon will allow Game Freak to focus development on other aspects of the game!
:D
If we look at past Pokémon games, the number of available Pokémon in sequels or follow-ups has varied significantly. The jump from Red/Blue (151) to Gold/Silver (251) was a major expansion, introducing 100 new Pokémon. However, later generations have handled sequels and follow-ups differently.
X & Y featured 721 Pokémon, but when we consider follow-ups like Sword & Shield or Scarlet & Violet, we see that the total number of available Pokémon in a single game is often lower than the full Pokédex at the time. This suggests that a sequel to X & Y might not necessarily include all 721 but rather a curated selection, possibly capping out around 240 Pokémon, depending on design choices, balance, and development priorities.
Of course, this is just speculation based on trends, but it wouldn't be unprecedented for a sequel to focus on a smaller roster rather than the full national Pokédex.