Why is this a thing

Fun fact: Leafeon doesn't need grass energy to function. And that means Celebi doesn't either.

And if you use Water energy instead, then you can add Manaphy and Iridia alongside Erika to the deck.

And there's also a tech you can do with 2 Leafeons: With 1 Leafeon in the Active Spot, use its ability. Then retreat to your second Leafeon (or Manaphy) with an XSpeed or the energy you just gained and use its ability again. You just gained 3 energy in 1 turn and have an undamaged Leafeon on the Active Spot. Then next turn you can use Iridia to heal both cards.

Manaphy and some healing items could be swapped for other utility cards if you want.

Have fun