TALK TO THE AGENT LOOKIN' guy in liberty pier.
Use Surf in Driftveil and surf right. The iitem on the rocks is a Water Stone
route 6
water stone
It evolves with a water stone
Vaperon i think.
you evole it with a water stone
A Staryu evolves with a water stone.
So far (although I have completed White not yet Black) all I know are Pansage (Leaf Stone), Pansear (Fire Stone) and Panpour (Water Stone). Sorry if this isn't as helpful as you hoped!
set up a gallery in join avenue. Then wait until you eventually get a water stone from one of the items.
Lime Stone(Calcium Carbonate)
Petilil will evolve with a sun stone, pansage with a leaf stone, panpour with a water stone, and pansear will evolve with a fire stone.
You need to use a water stone