With Energy cards, you can charge up your Pokmon and attack other monsters on the battlefield
Obviously these cards were printed months in advance in time for shipping and logistics, sheet cutting, placing into packs / stater decks, ink testing etc
A lot of its power comes from partner, which allows you to pair it with another legend and broaden your deck's color identity and strategy
Exile cards from the top of your library equal to the excess damage dealt to that creature this way
This stuff really matters, and "the first time each turn" decreases fun more than it increases elegance
This expansion could bring new mechanics, characters, or even a shift in strategy