>>40438585Thanks to the anime, Charizard is literally the second most popular Pokemon of them all, just below Pikachu, and GameFreak's effectively made it the "badass mascot".
This, of course, means they have no reason not to pander to it, make it available and/or appear in the games whenever possible and give it every single shiny new toy, all for the sake of upkeeping its status and promoting merch sales based on it.