I have a friend who's trying to evolve a Feebas, but he doesn't have a Prism Scale. Anyone know where to find one?
You can find a Prism Scale on Exeggutor Island, off the coast of Poni Island. It is also possible to get one while fishing or through Pickup, although it is rare.
Source: Experience and Serebii
The best way to find a Prism Scale would be to go to Exeggutor Island ("all the way round to the north of the island" according to Serebii). However, Prism Scales are also available through fishing or via the Pickup ability, which has changed up a bit in Sun and Moon.
Hope I helped. :)
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