Most madness cards get a highly reduced cost when played for madness, so as long as you have a somewhat decent mana base on the field, you can draw a ton of cards while also playing everything you discard
So by PSA logic Venusaur becomes Machamp since they are both number 68
As for more Magic: The Gathering cards from this expansion, you can still get the MTG Avatar The Last Airbender Beginner Box at around $10 off on Amazon
That fundamental supply-demand dynamic, fixed supply meeting growing demand, is the engine that has driven vintage Pokemon card values upward for years, and it shows no signs of stalling
You can literally change every card in the game that's a Pokemon, so I'm sure there could be plenty that you could do to cards to change the difficulty
If your cards take up space in your house, then it might be time to sell them so you can free up some room