Logan Paul made two videos of 1st Edition Base Set box breaks, and there are a handful of other videos of people opening up 1st Edition or Shadowless booster boxes or packs
Reaper is just easy to include in decks with low cost, high base power and good synergy
To help you get a better idea of what plays contribute to what goals, here are some examples based on a theoretical match between Buzzwole-GX / Lycanroc-GX and Gardevoir-GX: Get You Closer to Winning Play Example #1: Using Guzma to bring up a Tapu Lele-GX and knocking it out with Buzzwole-GX's Knuckle Impact
Ancestral Recall draws you cards or forces your foe to, at instant speed, for by far the best base rate in the game, and with exactly zero drawbacks
With enough Energy, flipping tails a few times wont matter
Creatures died when they took damage equal to or greater than their toughness