The most egregious of these were restricted, but with so few of the powerful-yet-unrestricted cards we've gotten since, gameplay was focused centrally around restricted cards
You can only use 1 "Maxx "C"" per turn
We are certainly not shocked to see a Charizard card be the top of this expansion's most expensive list and we were absolutely right
Special Summon 1 "Gaia The Fierce Knight" monster, or 1 Level 5 Dragon monster, from your hand or Deck
In a Two-Headed Giant game, Thermo-Alchemist's activated ability deals 1 damage to each of your opponents, resulting in the opposing team losing 2 life
return those Effect Monsters to the hand/Extra Deck, then you can Special Summon 1 "Madolche" monster from your hand or Extra Deck with ATK less than or equal to the total original ATK of those returned monsters