Get an Eevee and level it up in the Eterna Forest.
In a battle at the top of Route 212
to get a leafeon in Pokemon platinum, you need to have an eevee and then at any lvl you have to use a leaf stone!
Pokemon Number 169 in Platinum is Leafeon
No.
Gardenia has one.
It is Leafeon.
(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).
in order to get a leafeon you will first need your eevee and then go into eterna forest and find the rock that is covered in moss. level your eevee up there and it will evolve into a leafeon :)
two trainers on the way to Pokemon mansion from pastoria have them.
At the top of route 212 the ranger has 1
Personally, I like Togekiss, Snorlax, Blissey, Leafeon and others
By trading across from either Pearl, Diamond or Platinum version