In Castelia city when you first enter the city you go down towards the first opening near the dock and talk to the scientist looking dude i think is what he looks like. Hell ask you which of the monkey looking Pokemon you got and whichever you choose hell give you the stone for it:
Pansear: Fire Stone
Pansage: Leaf Stone
Panpour: Water Stone
I don't know if there is another way of getting a leaf stone but that's one way you can get at least one.....hope that helpd =)
Pansage will evolve by using a Leaf Stone into Simisage.
The only Unova Pokemon that evolves with a Leaf Stone is Pansage.
route 6
pansage
hm im not sure
give it a leaf stone
Go to black city and gain people from pokemon white's white forest who gives you the option of selling leaf stone. After, save, go to the market that just appeared in your city and buy (expensive) leaf stones.
Pansage
use a leaf stone on it
catch an eevee and use a leaf stone on it
The Leaf Stone can only make 5 pokemon evolve. Gloom into Vileplume, Weepingbell into Victreebel, Exeggcute into Exeggcutor, Nuzleaf into Shiftry, and Pansage into Simisage.
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.