The moves a Pokémon can learn may differ between Pokémon Legends: Arceus, Pokémon Brilliant Diamond, Pokémon Shining Pearl, Pokémon Sword, Pokémon Shield, and other Pokémon games. For this reason, if a Pokémon is moved via Pokémon HOME to a game where it cannot learn its current move set, then its move set will be replaced with moves that it is able to learn in the target software.
Your Pokémon’s move set is saved for each game that you have linked to Pokémon HOME. This means that even if its moves change after being transferred to a game where all or some of its original move set is unavailable, returning that Pokémon to a game it’s been to before will restore the last move set it had prior to being transferred out of it.
Special note regarding Pokémon: Let’s Go, Pikachu! and Pokémon: Let’s Go, Eevee!
Pokémon caught in Pokémon: Let’s Go, Pikachu! or Pokémon: Let’s Go, Eevee! that are moved to Pokémon Sword or Pokémon Shield will retain their original move set.
However, note that Pokémon moved from Pokémon: Let’s Go, Pikachu! or Pokémon: Let’s Go, Eevee! to Pokémon Legends: Arceus, Pokémon Brilliant Diamond, Pokémon Shining Pearl, Pokémon Sword, or Pokémon Shield cannot be moved back to the Pokémon: Let’s Go, Pikachu! or Pokémon: Let’s Go, Eevee! titles.