I've got to admit, that's an interesting concept for a change in the battle system. It somewhat reminds me of the Pokémon TCG series that I used to frequently play a few years ago. The TCG system would require you to wait until you had enough energy attached to the Pokémon before being capable of performing most attacks. More powerful attacks would require more energy, and certain attacks disposed of your Pokémon's energy. I'm a fan for any changes to the current battle system. Yours has potential to increase the realism of battles, since it seems to better match the actual strength of a Pokémon.