After you beat 8 gyms proffeser elm gives you it dummy
You find it at the top of the Tin Tower after having gotten the Rainbow Wing.
In navel Rock
you can probably find it on Ebay
In Route 44.
You can find one on Route 44.
pokemon heart gold
after you beat the elite four, you can go to to the Kanto region. (at least i think its Kanto its the one with Brock and misty) at the first city, pewter town, there is a man next to the Pokemon center after you beat Brock he will give you the silver wing (gold version) or the rainbow wing (silver version).
on route 44 you will find him
The tower
in golden rod city
Must evolve it or trade it.
You have a tiny chance to find one in Dragon's Lair.