Manga move errors
In the Pokémon manga, a situation will sometimes occur in which a Pokémon knows a move it cannot learn legally 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.
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 manga Pokémon with moves that they cannot learn in the games
|Ruby's Nana||Hyper Beam||Hanging Around With Slaking I||Norman mentioned that he taught Nana how to use Hyper Beam before the start of the series. However, Poochyena is unable to learn Hyper Beam before evolving into Mightyena.|
|Y's Fletchy||Ember||Fast-Thinking Froakie||Y told her Fletchy to use Ember, but the move was never seen being executed. However, Fletchling is unable to learn Ember before evolving into Fletchinder.|
|Gold's Pidgey||Peck||The Legendary Pokémon Appears!|
|Gold's Bayleef||Stomp||Extreme Power!! The Friday Pokémon|
|Satoshi's Charmander||Tackle||Prologue: Pallet Town|
Pokémon in How I Became a Pokémon Card will often use moves that they cannot learn in the games. These are generally not errors, though, because this series is based on the Pokémon Trading Card Game; the "illegal" moves Pokémon use in this series are moves from their TCG cards.
|Blaine's Arcanine||Fire Spin||Cinnabar Island||Blaine's Arcanine uses Fire Spin in the chapter. However, Arcanine was unable to learn Fire Spin until Generation II.|
Similar examples that are not manga move errors
Pokémon which can know the move in a previous game
|Ash's Charizard||DragonBreath||Off To The Battle Frontier!!||Ash's Charizard uses DragonBreath, which though impossible for Charizard to have in Generation III onward, was available to teach to Charizard by TM24 in Generation II.|
|Gengar||Double-Edge||Tears and Emotions - It's the Final Chapter!||Gengar uses Double-Edge, which though impossible for Gengar to have in Pokémon Mystery Dungeon: Red Rescue Team and Blue Rescue Team, was available to teach to Gengar by TM10 in Generation I and Move Tutor in Pokémon FireRed and LeafGreen, Emerald, and XD.|
|Red's Clefairy||Rage||Clefairy Transforms?!||Red's Clefairy uses Rage, which though impossible to have in Generation III onward, was available to teach to Clefairy by TM20 in Generation I.|