* Pokémon Diamond's Pokedex: Pokémon Diamond has a limited Pokedex. It only features Pokémon from Generation IV (including some from Generation I and II).
* No. 65 - Alakazam: Alakazam is a Psychic-type Pokémon from Generation I, so it is NOT in the Diamond Pokedex. You won't find it naturally in the game.
* No. 115 - Kangaskhan: Kangaskhan is also from Generation I and is NOT in the Diamond Pokedex.
How to Get Them (Unofficially):
* Trading: The only way to obtain these Pokémon in Diamond is through trading with someone who has them.
* Events: Occasionally, Nintendo has events that allow you to get certain Pokémon in games they are not normally found in. You would need to have participated in a past event or have a save file from a game that did.
Important Note: It's against the rules of competitive Pokemon battles (and many online communities) to use Pokémon obtained through illegal methods.