Quote Originally Posted by Pokemon Fan
What could possibly be a better introduction than in a battle with a Legendary Pokemon?
Well, okay, it was amazing enough. But I mostly meant it wasn't a proper introduction for a special attack like that. Blast Burn was very unique in the games, so for a Pokemon to learn it just by trying hard is sort of lame to me.

Well according to the dub at least Charizard didn't "suddenly" learn it, at least that's the impression I got. Ash exclaimed something like "wow, you taught yourself that attack all by yourself?"
Yeah, you're right. But ditto to my last paragraph.