Pokémon: Let's Go, Pikachu! and Let's Go, Eevee! are now the fastest selling Nintendo Switch titles, having sold over 3 million copies in their first week of release. While the titles have outsold Switch champions like Super Mario Odyssey and Breath of the Wild, they have a bit more ground to cover to join the success of other Pokémon titles.
https://www.notebookcheck.net/Pokemon-Let-s-Go-sells-3-million-copies-in-its-first-week-becomes-fastest-selling-Switch-game-ever.366726.0.html