That is a real concern when dealing with water pokemon. Especially in arid locations. There are some things they sell in the pokemarts that help keep water pokemon from drying out on land, special cremes and oils and such. And I've also heard some people swear by using the fluid excreted by Pyukumuku to help keep the scales of their other water pokemon healthy and moist while on land. Thankfully I don't have to worry about that too much, not when the ocean is so close by.

What kind of pokemon is Oku?