Mega Rayquaza has lived through several of these eras, so here's a quick guide to how they work
In this set, Pokmon revealed a comeback mechanic ACE SPEC where the deck can only have 1 ACE SPEC card inside which has a powerful effect
Create a 1/1 white Soldier creature token for each permanent exiled this way
One creature in particular from that set, Monastery Swiftspear, was reprinted for Standard and remains such a potent card that she sees play in Modern burn decks
Interestingly, this deck will have two face cards, with Sam, Loyal Attendant serving as a partner commander with the unrevealed Frodo, Adventurous Hobbit
While I dont have the data to prove the trend, certainly from my own experience the more generous a set, the more of my money I want to spend on it