Blastoise isn't the most popular of all the original starter Pokmon but in the world of the trading card game, he is among the most expensive for collectors
Short answer: it depends on why you collect (prestige vs play vs long-term resale) and what you collect (rarities, promos, graded grails)
You +1 it to attach to your critter and then it now cannot be attacked to be killed, it gets a +1/+1 counter and then when the attached dork smashes face, you put that many loyalty counters here
One for each major (150+ card) set ranging from Foundations 2024 through Alpha
If Lord of AtlantisLord of Atlantis is in a list, you can predict, pretty confidently, that most creatures in the deck are Merfolk
Some creatures like Steel Seraph and Phyrexian Fleshgorger have seen a small amount of Standard play