Sometimes Clefairy can be holding a moon stone with them, so my advice is to go to Mt. Coronet and try your best to catch one.
No, you can't go to the moon
Clefairy is the only Pokemon in pearl that evolves with a moon stone but once you get the national dex you can evolve Jigglypuff, Nidorino, Nidorina & Skitty
New moon island is only avalible in Pokemon pearl, diamond and platinum
Jigglypuff, Celefairy, Nidorino, Nidorina, Skitty.
you need a moon stone
you have to give it a moon stone
It's on New Moon Island
To the MOON!
You catch Cresselia
head east from full moon island to get to new moon island
Fly like a bird, or else you can't. Long story short, you can't get to Mt. Moon in Pearl. At least, I THINK you're talking about Mt. Moon.
Underground you can also migrate it but I suggest you don't