>>28929886This is the reason people say Greninja is the new Charizard. Because they came to be popular in nearly the same way. The only advantage that Charizard had over Greninja was that he appeared on the Box Cover, which is admittedly big promotion in itself, but either way, so did Blastoise.
Both Charizard and Greninja were instant hits since the game released. Literally everyone i knew near instantly was asking for Shiny Froakies or even breeding for them shortly after buying the game. You would be hard pressed to find someone who didn't consider Greninja as the best Pokemon of Gen VI even that very same October the game released, with its only rivals being maybe Sylveon, Tyrantrum and Yveltal. Charizard's main competition was Mewtwo, Dragonite and Gengar, but he remained as most people's favorite either way.
They managed to nearly replicate Charizard's success, with the core difference being that we don't live in the Age of Pokemania, so it was even harder to do something like it.