Its definitely not a case of one deck simply beating the other
10 9 Ceruledge EX #147 One Of Only A Couple Of High-Value Cards That Aren't Eeveelutions Estimated Value: $157.00 (Ungraded) - $840.00 (PSA 10) This set is filled with high-value Eeveelutions
If the search is simply for a number of cards without stating a quality, you must have them find that many cards (or as many as possible, if their library doesn't contain that many cards)
The set they are from will be random
A useful Rule 0 explanation can be as simple as: "My deck is an upgraded precon, has no fast mana, and can win with a three-card combo after turn seven." This would tell the table far more than simply saying, "It's about a seven out of 10." Rule 0 can also be used to modify parts of the format
Because they (unsurprisingly) have attacks that deal 300 damage, some have noted that their unplayability prevents their price from shooting through the roof on the secondary market