(Sorry i though for a second you said "Why do you have to find Misty")
(This question needs to be improved)
She is in Cerealen City.
You can't find her anywhere in the game.
Where you find Misty.
in your face is where you find it haa
Once you beat the Pokemon League at the Indego Platue, you will be able to go to Kanto and see Misty.
You can find Misty in Pokémon Crystal in Kanto Region. You will find her north of Cerulean City where she is with the man she is dating.
You can find Cranidos in Cerulean City where Misty is.
cerulean city kanto.hope it helps!
She's at the end of route 25
On the bride on route 25
after you fix the power plant,go to rt.25,the hill,and you'll see misty.
misty is not on emerald