None really, because I don't have it, but I guess I feel bad that players can't 100% the pokedex on switch because of the Elemental monkeys. But maybe in ZA?

Nidoran (both genders), Wynaut, Nincada, The rest of the fossils, and Scolipede

All 3 members of the Roselia Evolution line (My favourite) arent in Gen 9 main game. Neither in the DLC's

None because All the Starters are in the game.