They enable surprise plays, counter enemy spells, and provide combat tricks that keep opponents guessing
D Team ZEXAL chapter 6: "A Duel with the New Deck!!" Yu-Gi-Oh
Players cannot attack each other, but they can use cards to protect teammates and attack adversaries that are in front of any player, not just their own
As Christmas nears, the group, run from Manchester by three men in their 20s, has shifted to Pokmon cards
Given there were originally 15 types of Pokemon back in the Red and Blue days and that has grown to 18 over the years, it makes sense to simplify things for the TCG
If Primeval Spawn would enter the battlefield and it wasnt cast or no mana was spent to cast it, exile it instead makes it so you cant Reanimate, Sneak Attack or Polymorph it into existence and this design choice feels very deliberate