This can be copies of a specific card (e.g., 4 copies of Lightning Bolt) or the total count of cards serving a particular role (e.g., 10 removal spells, 24 lands, 14 blue sources)
These are the defining rules that make a deck legal but its important to note there are further considerations to be made when creating a functional, powerful deck
Between multiple good Commons, access to plentiful removal, late game threats like Monoist Circuit-Feeder and Thrumming Hivepool, this UB deck was able to take a Trophy too
The store pages for the app also confirm that players will be able to open two free booster packs per day, not dissimilar to other mobile card games like Yu-Gi-Oh: Master Duel
Once you've discarded those two cards, you can add the Pokmon you searched for to your hand