You attach energy cards to critters so they can perform attacks, and you can evolve one Pokmon into another if you've got the right cards
It makes your opponent skip their Draw Phase
The Cards in Promo Pack A Vol.2 are Highly Desirable These cards are extremely desirable, with Venusaur being the most visually striking
Swiftfoot Boots is another great piece of protective Equipment, but its been printed so often that copies are only about $1
and of course Jace, the Mind Sculptor were dominant in their times in Standard, and in the case of Jace, in older formats as well
Reminders on terminology: prismatic Ultimate and Collectors Rares are new technologies that premiered in Rarity Collection, then re-appeared in Rarity Collection II and nowQuarter Century Bonanza