I'm not counting Shiny-locked Pokemon.
Friend Safari Pokemon
Poke Radar in XY before a chain of 40
Non-legendary Pokemon in the Ultra Wormhole
Galarian fossil revives
Max Raid Battles
Regina trades in IOA
The Regis in Swsh
The Swords of Justice in SWSH
Impidimp and Morgrem static encounters
Spiritomb in SWSH
Literally everything in BDSP other than eggs.
Source: Combing Bulbapedia and Gamefaqs for an hour