Here's why:
* Breeding Mechanics: In Pokémon Emerald, eggs are created by breeding two compatible Pokémon of opposite genders.
* Skitty's Gender: Skitty is a genderless Pokémon, meaning it cannot breed on its own.
* Ditto's Role: Ditto is a Pokémon that can transform into any other Pokémon. It's the only Pokémon that can breed with any other Pokémon, including genderless ones.
Therefore, to get a Skitty egg, you must use a Ditto and breed it with a Skitty.
Here's how to get a Ditto in Emerald:
* Route 119: You can find Ditto in the tall grass of Route 119, although it's relatively rare.
* Trade: You can trade for a Ditto with other players.
Once you have a Ditto, you can breed it with your Skitty to get Skitty eggs.