In Pokémon Black, you can receive a Water Stone from a person in Castelia City provided your answer to his question is Panpour. Additionally you can find Water Stones within Dust Clouds that appear in Driftveil City, Wellspring Cave, Mistralton Cave, Chargestone Cave, Challenger's Cave, Giant Chasm, Twist Mount and the Victory Road.
the bays at castelia city
No
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.
I know pansear does. you receive it if you have a water type starter.
staru evolves by a water stone
You need to use a water stone
Staryu evolves into Starmie when you give it a Water Stone.
you need a water stone for staryu to evolve into starmie :)
Panpour evolves into a Simipour when you use a Water Stone on it.
you can use a water stone on lombre
There is no Pokemon in sinnoh that evolves by a water stone.
Here are some stones and the Pokemon that they evolve... Leaf Stone: Evolves Pansage into Simisage Fire Stone: Evolves Pansear into Simisear Water Stone: Evolves Panpour into Simipour Moon Stone: Evolves Munna into Musharna Sun Stone: Evolves Cottonee into Whimiscott (Black) or Petilil into Lilligant (White)