Aside from Contact Fusion Monsters, Fusion Monsters are primarily the only Extra Deck monster card type that can only be Summoned from the Extra Deck through card effects
It evolves from Impmon, and can evolve into Mummymon, Algomon (Perfect), or Wisemon
I support weighing I may get off on the wrong foot in the community by saying this, but I will stand behind this
It features the Disney characters and heroes we all know through superbly illustrated cards
For how to build a pokemon tcg deck, disassemble a theme deck and rebuild: Keep the core Pokmon line, upgrade Trainers with better draw (e.g., swap for Professor's Research), and adjust Energy
Extremely unlikely, when you think about high profile wealthy Magic players like Post Malone, Hunter Pence, Cassius Marsh, and so on