Why can't my Charizard learn Blastburn ?

Question

In Pokemon Firered, my charizard is not learning blastburn. At cape brink, the person said "Oh, I wad mistaken." I traded a bulbasaur from another game, but it teaches frenzy plant to Venusaur. In small words, my starter cannot learn the special move but the Pokemon I traded can learn that. How should I fix that?

Comments

Not a full answer, but https://bulbapedia.bulbagarden.net/wiki/Cape_Brink

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Was this your starter Charizard? The only one you had? If you'd taught Blast Burn to a previous Charizard then the move tutor wouldn't teach it again. Oh and max happiness is a must, usually it's a given for a fully evolved starter to have max happiness but double check that if possible?

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Charizard was my starter, it had max happiness, it was fully evolved and I didn't had taught it to any other Charizard, too.

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Weird. Did you perchance teach it to a Typhlosion? Bulbapedia mentions Kanto Starters only but I'm grasping at straws here.

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Can you show us a video?

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The Pokémon must have maximum friendship and each of these moves can be taught only once.