Now that Sword & Shield is out, fans are free to pick through the game’s code, and of course one of the first things that’s being done is the addition of some Pokémon that didn’t actually make it into the game.
The model and animations were imported from Pokémon: Let’s Go, and the most important thing here is that the Omastar was added to the game as an all-new entry whose stats can be edited, not just a replacement for a Pokémon already in the game. So theoretically, you could keep adding Pokémon and flesh out Sword & Shield’s Pokédex, with the biggest problem coming from the fact that while it’s relatively easy to import models from Pokémon: Let’s Go, adding other Pokemon from later games would take a ton of work to get stuff like their animations working properly.
This is a good start! It’s far from a seamless fit, but to get something like this working so well so quickly after release—SciresM says “To be clear, this is the Let’s Go model imported with literally no changes on my part”—points to good things being done in this space in the weeks and months to come.
Obviously all this work is being done on PC, which is able to run many Switch games in let’s say an unofficial capacity.