you dont Bebe gives you Evee in Heathrome
You can't evolve it but i think you can catch it because i have glaceon. I'm not sure if u can catch a leafeon i have caught or seen shiny of most of the eeveelutions including, umbreon, glaceon, espeon and eevee (I also have caught them all shiny) i have heard of people seeing vulpix however I'm yet to see a leafeon sorry
You can catch Leafeon in Celadon City where Misty is.
Glaceon doesn't exist in firered.
you can't you have to get an evee
Leafeon is a fourth generation pokemon, so you cannot own it in ruby (a third generation game), let alone catch it.
catch an eevee and use a leaf stone on it
you can't find leafeon or glaceon, you need to transfer an eevee from one of the gameboy games or gts trade for an eevee then in the etherna forest there'll be rock mossy rock, have your first in your team and either touch it or i think you might have to fight a wild pokemon next to it or something and your eevee will evolve into leafeon
catch an eevee from trophy garden and level it up in eterna forest near the mossy rock and it will evolve into a 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).
it doesn't exist in the kanto, johto, or hoenn region. it is a sinnoh only pokemon, a new one.
Vaporean can be found at Almia Castle and Altru Tower. Jolteon in Haruba desert. Flareon in Volcanic cave. Espeon in Hippowdon Temple. Umbreon in the Chroma ruins. Leafeon in Vien Forest and finally, Glaceon at the Ice Lake.
???? sorry i do not know You do not catch glaceon, you evolve it from an eevee. I think it is somewhere on the way to Snowpoint City