Here's why:
* Pokerus is random: It's a chance encounter that occurs when a Pokémon battles another infected Pokémon.
* No cheat codes: Pokemon Diamond doesn't support cheat codes that can give you Pokerus.
How to find Pokerus:
1. Trade with others: The most common way to get Pokerus is by trading with other players who have infected Pokémon.
2. Battle wild Pokémon: There's a small chance a wild Pokémon in your game could be infected with Pokerus.
3. Keep breeding: If you're breeding Pokémon, there's a chance the offspring could inherit Pokerus from the parent.
Remember: Pokerus is a temporary condition. It will last for a few days, and your Pokémon will still benefit from it even after it disappears.
Let me know if you have any other questions about Pokémon Diamond!