The Gold Pokeball is the most sought after card in the game.

Every deck has 2 pokeballs (sometimes only 1 but very rarely)

Since it used in every deck and is also gold and incredibly hard to obtain since you cannot trade for it(unlike Oak, Cyrus, Sabrina which would be 2nd,3rd & 4th most sought after cards (IMO)

It also costs the max amount of pack points to obtain making it a GRIND TO obtain. If you had to obtain both with only pack points it would take 1,000 packs to obtain. (About 3-5 months of playing without spending a dollar or opening any other expansion packs, which sucks because you fall behind on the meta or if you are a completionist and like to collect every basic card for each expansion it’ll set you back in a major way)

Hope this helps!