They are the Blastoise and Charizard or Agumon and Gabumon of Yu-Gi-Oh
Steam Gyroid!" Most of the time when Syrus declares an attack with that monster, he announces "Steam Gyroid attacks!", followed by "Train Twister!" When Syrus Summons "Ambulanceroid", he announces "Ambulanceroid is coming to the rescue!" Most of the time when Syrus declares an attack with that monster, he announces "My Ambulanceroid attacks!" When Syrus activates that monster's effect, he announces "Ambulanceroid's effect activates!", followed by "I Special Summon the "roid" I added to my hand!" When Syrus Summons "Carrierroid", he announces "I summon Carrierroid!" Most of the time when Syrus declares an attack with that monster, he announces "Full speed ahead, Carrierroid
To begin, players place Basic Pokmon in their play area face down
At first, the large supply of these cards makes their value low, but over time they can grow more valuable
It was Magic artist and then-Wizards-employee Christopher Rush who started the idea*
Whenever a player draws their second card each turn, put a +1/+1 counter on Krang
