..Uh...i think you mean the Pokemon mansion...that's on cinnabar island...youd haf 2 surf 2 ther from pallet town if u havnt been there...othrwize fly there...cuz celadon duznt hav a mansion...it duz...
it is 3 houses left of poke center
Go around the back and follow the stairs all the way up. There will be a small building. Go inside and take the pokeball on the table to get an eevee.
Get the national dex
Its not in Pokemon pearl the celadon mansion is in firered, leafgreen and red, blue and yellow.