Here's why:
* R4 cards are flash carts: They act as external memory for the Nintendo DS.
* Cheats are stored on the R4 card: Cheat codes are stored on the R4 card and loaded into the game when it's running.
* R4 software handles cheat execution: The R4 software on the card interprets the cheat codes and modifies the game's data in real-time.
Without an R4 card, you cannot use cheats on Pokemon Pearl.
Important Note: Using cheats can significantly detract from the experience of playing Pokemon Pearl. They can make the game too easy, spoil the intended challenge, and disrupt the balance of the game.