From Bulbapedia, the community-driven Pokémon encyclopedia.
In the Pokémon anime, there will often come up a Pokémon that knows a move it cannot learn legitimately in any of the games. It is unknown whether these are actual mistakes, a writing policy of not having to stick to the games too closely, or merely the Pokémon using an attribute that shares the name of a move in the games. In Bulbasaur... the Ambassador!, Professor Oak states that in times of need Pokémon can call upon power never known to it previously, such as Ash's Bulbasaur learning Dig.
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 anime Pokémon with moves they cannot learn in the games
Japanese version only
Similar examples that are not anime move errors
Pokémon which can learn a move in a previous generation
|| First use
|| Mr. Moore's Typhlosion
|| Poetry Commotion!
|| Mr. Moore's Typhlosion uses Headbutt, which, though impossible to have in Generation III, was available to teach to Typhlosion by TM02 in Generation II and via Move Tutor in HeartGold and SoulSilver.
In the dub, the move was referred to as Tackle instead, a move Typhlosion could learn in Generation III.
| Andi's Nidoqueen and Oscar's Nidoking
|| The Bicker the Better
|| Andi's Nidoqueen and Oscar's Nidoking use Submission, which, though impossible to have in Generation III onwards, was available to teach to Nidoqueen and Nidoking by TM17 in Generation I.
|| Ash's Charizard
|| The Symbol Life
|| Ash's Charizard uses DragonBreath, which, though impossible to have in Generation III onwards, was available to teach to Charizard by TM24 in Generation II.
|| Anabel's Espeon
|| Zap Cannon
|| Second Time's the Charm
|| Anabel's Espeon uses Zap Cannon, which, though impossible to have in Generation III onwards, was available to teach to Espeon by TM07 in Generation II.
|| Virgil's Vaporeon
|| Team Eevee and the Pokémon Rescue Squad!
|| Virgil's Vaporeon uses BubbleBeam, which, though impossible to have in Generation III onwards, was available to teach to Vaporeon by TM11 in Generation I.