Once they have, you can ready any chosen character
The Pokemon TCG: Sword & Shield expansion includes a total of 202 different cards
Given the small roster of Primal options, Jumbo cards are included, though the artwork is identical to other, standard-sized cards
Based on this, I think the best guess is that the Gold Stars are printed on the same sheet as the holos, with each one (Flareon, Jolteon and Vaporeon) appearing twice on the sheet, yielding 2 x 3 / 121 * 9 = 0.446 Gold Stars per box
Steven Stone, Champion of the Hoenn League, appears in Scarlet & VioletDestined Rivals on a series of Trainers Pokmon cards that, when played right, can boost Energy acceleration while reducing damage to any of Stevens Pokmon that you have on your team