Unlike previous Mainstream Pokemon Games, not every single Pokemon was coded within Pokemon Sword & Shield originally. Instead, only the new 81 8th Generation Pokemon, along with 319 Legacy Pokemon and 35 Transfer Only Legacy Pokemon could ultimately be obtained in Pokemon Sword & Shield. Since then, the DLC Expansion Pass has brought the new areas of the Isle of Armor and the Crown Tundra to The Galar Region, along with hundreds of Legacy Pokemon not originally released within Pokemon Sword & Shield.
However, still not all nine hundred or so Pokemon known to exist can be found in Pokemon Sword & Shield. If a Pokemon is not found within the 400 Entry Galar Region Pokedex, 211 Entry Isle of Armor Pokedex, and 210 Entry Crown Tundra Pokedex and is not one of the select few Transfer Only Pokemon, it effectively cannot be obtained in these two games. With that said, however, this does not mean that the Pokemon Company will not eventually release another update some day down the road that will allow trainers to find the rest of the Known Pokemon within The Galar Region.
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