A few things that make it stand out: Leader cards & colour identities You build decks around a Leader (Luffy, Law, Zoro, etc.), which defines your colour(s) and playstyle
Look in either the bottom right-hand corner of the Pokmon illustration or on the bottom right-hand corner of the card for the set symbol
"They don't have any numbers or set symbols." Of the 36 CoroCoro promo cards, there are several that stand out, including the glossy Ivy Pikachu single, which, along with the Jigglypuff glossy card, was the first to be released
Essentially, this the gameplan for how you will want to play this deck
If you scan weekly, speed and consistency matter more than subscription price