Dialga EX & Yanma EX (Space-Time Smackdown) Gyarados EX & Greninja (Mythical Island) Mewtwo EX & Gardevoir Pikachu EX & Zapdos EX A Tier For the A Tier decks, these are close to S Tier in that they're either consistent or powerful, but they're not both
Special Guest cards are found in set boosters from only one set
You can cast Bello fairly early thanks to its low casting cost, allowing you to immediately start animating your permanents into big threats
Dropping some of these cards on Turn 1 can set you up for success, so you should definitely consider adding them to your builds
2-3 Booster Packs: Rare Candy, Full Art Zekrom/Reshiram, very strong/needed rare cards (Emboar Ability usually goes for 2 more often than 1), all Prime Cards other than Zone, Mega, and Donphan