In the Nintendo DS game of Pokémon Pearl, there is no evolution stone that will induce evoluton in Eevee that will allow it to evolve into Leafon however Eevee will evolve into Leafeon once it levels up near a Moss Rock, you can find the Moss Rock in Pokémon Pearl in the Eterna Forest.
you can't. there's no moss-stone to evolve it, so you'll need to trade it from diamond, pearl or platinum
You have to get it from a friend who has Pearl/Diamond/Platinum
Evee will never evolve to leafeon in firered because leafeon wasn't created until diamond, pearl and platinum came out meaning it doesn't exist in firered.
Eevee can't evolve into leafeon in soulsilver you have to trade it to diamond and pearl and evolve it there. The ilex forest doesn't have a Mossy Rock - which is what evolves eevee into leafeon.
By trading across from either Pearl, Diamond or Platinum version
You have to trade it from Diamond, Pearl, or Platinum. You can't evolve Eevee into it in HG/SS.
you get a leafeon by going to eterna forest with an eevee. Go to the mossy stone(hidden so use some repels)then level up your eevee and it will evolve into a leafeon.
In Pokemon Diamond/Pearl, you find a old man at route 212 with a Leafeon.
Contrary to popular belief, eevee does not evolve into leafeon by using the leaf stone. To evolve eevee to leafeon you must level it up by the mossy rock in the Eterna Forest. Other Pokemon that evolve using the leaf stone are: gloom to vileplume, weepinbell to victreebell.
(dim wit) You can't catch them in Pokemon Leaf Green because Leafeon and Glacieon was discovered in the Sinnoh region (Diamond, Pearl, and Platinum).
Contrary to popular belief, eevee does not evolve into leafeon by using the leaf stone. To evolve eevee to leafeon you must level it up by the mossy rock in the Eterna Forest. Other Pokemon that evolve using the leaf stone are: gloom to vileplume, weepinbell to victreebell
It can evolve anytime after it learns the attack "Rollout".