I would suggest digging in the underground. You need an explorer kit to get to the underground.
you have to either find it by going underground
Use a moon stone on it
You can find one with Cleffa or Clefairy (5% chance) or you can dig underground.
You can get a moon stone by mining under ground with the explorers kit in hopes to find one.and i heard u can use thief on a cleffa and you might get a moon ston.(underground you can get more stones)
you need the downsing machine app and there should be one in enterna city and in mt cornet
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
digging under ground,o course.
you have to give it a moon stone
you need a moon stone
You find it in Mt. Moon
to get a moon stone on emerald you shold find sum in caves (hidden)
a stone that you find in mt moon that evloves clafairy to cafable