From Bulbapedia, the community-driven Pokémon encyclopedia.
In the Pokémon Trading Card Game, there will often come up a Pokémon that knows a move it cannot learn legally in any of the games.
Occasionally, in-game event Pokémon that can be transferred onto the main series games have a move that is not normally included in that Pokémon's moveset (a prime example being Pokémon Box Ruby & Sapphire, which gave away four separate Pokémon with moves that were not normally available to that specific Pokémon).
List of TCG Pokémon with moves they cannot learn in the games
Diamond & Pearl Series
HeartGold & SoulSilver Series
Black & White Series
XY BREAK Series
Game Boy's TCG-exclusive cards