>>41301859This. Think about this logically, anons. The 3DS' cartridges are much larger than the Switch's, so you can fit more Pokemon in them. They had to cut Pokemon otherwise they wouldn't fit on the cartridge.
Even with modern compression algorithms you can only shrink a pokemon down so much. Larger Pokemon like Wailord will still take up maybe a square millimetre.
A 3DS cart has 4.65cm^3 of storage volume. A Switch cartridge only has 1.95cm^3.
As evidenced by the GameBoy's massive cartridges but meagre 151 Pokemon, we can see that compression algorithms have gone a long way to shrink things down. However, Moore's law stopped being true at some point during the DS's lifespan - hence the smaller difference in size between BW's Pokedex and SuMo's.
Anyway, it's hard to compress such a large number Pokemon into what is less than half the volume. You need to remember Pokemon some are really, really big - like Arbok, which is over 11 feet tall! When you think about it like this it's only natural for GameFreak to have to can some. (I'm personally really upset over losing Roserade).
The reduced storage volume of Switch cartridges will likely have an adverse effect on any game with a lot of things to collect - case in point Pokemon SwSh.
