Your game is Pokemon Battle Trozei, because Pokemon Trozei only have from Bulbasaur to Deoxys.
So in Pokémon Trozei there isn't Leafeon.
In Pokémon Battle Trozei -
In Pokemon Battle Trozei you can just find all Pokemons in HERE , you can see their Type/Name/Power/Ability/ and Requirements!
Leafeon can be found at Zone 11 ''Safari Jungle'' at Stage 3 at Tuesday!
Have 3 Stars in Power/ Ability - None / Requirements - Bring Eevee as Support!
THIS is here you can find Leafeon details, go to Tuesday and Stage 3.
Hope this helps!