There was a leafeon/magmortar deck way back that I thought was pretty cool. Magmortar from secret wonders does 20x the number of fire energy attached to itself, and with leafeon you power it up twice as fast. Magmortar lvl X also benefits, it snipes for 100 but needs four fire energy, so with leafeon you can get it going in two turns. Add things like warp point, switch, and warp energy and you can be using the snipe attack every turn. The lvl X's pokepower is fantastic, and the regular magmortar's pokebody is really good too, taking off potentially 40 damage from it every turn. The weird thing about leafeon is that you can stack it if you have two, so if you get the deck set up fast enough you could be powering up two magmortars.