Where lighting Pokemon on emerald?

You can't "light" Pokemon in Pokemon Emerald. You can't manipulate their lighting or change their appearance in that way.

Perhaps you're thinking about:

* Using Flash: This move can temporarily blind opponents, making them less accurate with their attacks. You can teach Flash to certain Pokemon.

* Using a Light Stone: This item can evolve certain Pokemon, like Eevee to Flareon.

* Certain Abilities: Some abilities like Illuminate increase encounter rate at night.

Can you please clarify your question? Tell me more about what you are trying to do and I can help!