RGBY(13)→GSC(22)→E(14)→Pt(13)→BW(16)→BW2(13)→XY(13)→SM(16)→USUM(17)→SwSh(11)→SV(14) You place all 160 cards in the right order, one at a time. Three wrong guesses ends the run.
Gym Leader / E4 / Champion / Captain / Kahuna order is a free ordering game you can play right in your browser, with no sign-up and nothing to install. Every card hides where it falls in the sequence, so the whole run is really one big sorting puzzle. The first card comes up face up. After that you slot each new card into the spot where you think it belongs, and its value only shows once it lands. Guess wrong three times and the run ends with whatever you had down.
Here are 28 of the 160 cards you might be dealt, with 132 more in the deck. Their values stay hidden until you place them.