This thread is very clearly divided between people who understand what this actually means, which is just having the game data in the game so the competitive scene has access to the full roster, and people who don't
As recently as 2016 GameFreak did this, they've shown, over every generation, that programming that many pokemon isn't a problem, balancing that many pokemon isn't a problem, and as exhibited by the existence of the XY models in Sword and Shield, modeling that many pokemon is a largely solved problem