it's either you trade it for a green shard or you find it underground.
no
Buy it from the lilycove dept. Store :)
A Leaf Stone can be found on Route 119.
Go to liyovile city and then go to the general store and buy it
nowhere, find a green shard and bring it to the shard hunter near mossdeep city... he will trade it for a leaf stone
Lombre
To get the leaf stone in Pokémon Ruby you need to first go to the area of the Weather Institute. Next surf north to the waterfall and you will find the stone.
Nuzleaf will evolve into Shiftry and the leaf stone will turn Gloom into Vileplume.
Gloom
I am sure you get it from victory road.
gloom into vileplume.
Pokemon requiring a stone to evolve:Eevee - Thunder stone, Jolteon (you can't find this Pokemon in Ruby) Eevee- fire stone, Flareon (you can't find this Pokemon in Ruby)Eevee- water stone, Vaporeon (you can't find this Pokemon in Ruby)Sunkern- sun stone, Sunflora (you can't find this Pokemon in Ruby)Jigglypuff- moon stone, WigglytuffSkitty - moon stone, DelcattyNidorino- moon stone, Nidoking (you can't find this Pokemon in Ruby)Nidorina- moon stone, Nidoqueen (you can't find this Pokemon in Ruby)Growlithe- fire stone, Arcanine (you can't find this Pokemon in Ruby)Gloom- sun stone, BellosumGloom- leaf stone, VileplumeStaryu- water stone, StarmiePikachu- thunder stone, RaichuLombre- water stone, LudicoloNuzleaf- leaf stone, ShiftryVulpix- fire stone, NinetalesHappiny- oval stone Chansey