Sry buddy.
They do.
First gym is rock. need to evolve and get fighting type and still gets x2 from roxannes rock moves.
Second is fighting, neutral.
Third is electric. Can do something against the magnemite lines due to steel type. But do can Fighting moves. So fire is redundant at best.
Fourth is fire gym. rekt.
Fifth is normal. Fighting type again saving the day.
Sixth? Flying, now here the fighting type is a hindrance, but the fire type only deals with Tropius and Skarmory.
Seventh? Psychic. Fucks Blaziken's Fighting type. But Fire type sucks here due to secondary types.
Last gym? Water gym. Enough said.
Evil teams? Either fire/ground or water based teams. Fire sucks against both.
Elite 4? Dark? Neutral. carried by fighting.
Ghost? Neutral.
Ice? Would be ok if she didn't have water/ice bulky bois.
Drake and his dragons? KEKW.
Steven in R/S? Doable....but still pretty fucking bad.
Wallace in Emerald? Another water type roadblock.
Fire types are awful in gen 3. Doesn't matter if I love Sanji, fire hints and Blaziken is his signature pokemon.
Not to mention the sheer amount of water pokemon trainers in these fucking games.
SO.
MUCH.
WATER.