>>51578541Because Charizard was an unreliable super weapon of a Pokemon. He was like Ben 10's Alien X before Ben 10 was a thing. The allure of Charizard is the mystery of when will Ash be able to get Charizard to enter serious mode, because that's when the opponent is in trouble. After Ash gained complete trust of Charizard in the Poliwrath episode, they had to gradually tone him down to still allow Ash's other Pokemon to get their own spotlight moments.