Here's why this is:
* Item Availability: The Light Ball item is not available in Pokémon Emerald. It was introduced in later generations.
* Pikachu's Role: Pikachu isn't a particularly common Pokémon encounter in Emerald, and it doesn't have any special role in the game's story.
If you're looking for Pikachu in Emerald, you can find it in the following locations:
* Route 118: You can encounter a Pikachu in the tall grass here.
* Lilycove Department Store: You can buy a Pikachu from the Pokémon Fan Club in the department store.
Remember that Pikachu will not be holding a Light Ball in any of these locations.