Aipom is exclusive to Pokemon Black. It's part of the "Black/White" version exclusives, meaning certain Pokémon only appear in one version of the game.
To get an Aipom in Pokemon White, you'll need to:
* Trade with someone who has Pokemon Black: This is the most common method.
* Use a Wonder Trade: You might get lucky and trade for an Aipom through this method.
* Transfer from a previous generation game: If you have an Aipom saved in a Pokemon Black or older game, you can transfer it to Pokemon White using Pokemon Bank.
Let me know if you have any other Pokemon questions!