Since then, the deck has gone under several reconstructions and refinements, but Leafeon has stayed as a focal point of the deck. It is a very versatile card, and many people have their own strategies for it, but here is one way to play it:
Put leafeon out with one energy on it. If you've retreated something to put Leafeon out there, and you still have your energy for the turn, attach the energy to the pokemon you just retreated to remove two damage counters and begin building the pokemon back up again.
Your opponent attacks Leafeon. Watch; anything less than 50 is going to be negligible.
On your next turn, attach an evergy to leafeon to use plus energy and remove two damage counters. Put the energy you get to attach with plus energy on Leafeon. There, in one turn you've done 40, built Leafeon up for its Soothing scent next turn, and removed 4 damage counters.
If you don't need 60 to knock out the opponent and you still have energies, you can use plus energy next turn to add two "potion" energies-- as long as Leafeon is your active, you have a built in potion with every energy added.
This card is great for counteracting Poke-Bodies like Ampharos Prime's, which puts a damage counter on a pokemon for every energy you attach to it; with Leafeon out, this gives you a net gain of 1 damage counter removal per turn.
Leafeon's Pokepower can be augmented with the Dawn Stadium (Stadium) from Majestic Dawn, or Bellossom (Undaunted), which allows you to remove one damage counter from every pokemon once per turn.
Try it out!