Xpiicter

why would a starter pokemon not learn an attack wich is listed in the pokedex (at lvl 16)?

i leveld my charmander in viridian forest to level 15, then fightet ash and skipped lvl 16 and ended up lvl 17 at the end of the fight with an evolve request wich i canceld to learn dragonrage, wich wasnt possible. Charmande would learn dragonrage at lvl 16 but it didnt. Is there any way i can learn the attack before the first badge, because i need the attack to defeat brock. Pls Help