blackthorn city
It is not possible to get a ninth badge in Pokemon FireRed. You can only get eight badges in Pokemon FireRed.
to get the eight badge go to viridian city after you have 7 badges and enter the gym
in blackthorn city
get the eight badge or give it the soothe bell
you must beat the eighth gym leader and he will give you the badge.
beat 8 gyms
The gym is in Blackthorn City.The gym leader is Clair.
You get you 8th badge from Blackthorn City's Dragon Type Gym. Her name is Clair, and she owns a Lvl. 38 Gyarados (girl), a Lvl. 41 Kingdra ( girl), and two Lvl. 38 Dragonairs( both girls). I suggest using the super effective electric, ice, and dragon type moves. When you win, you'll get a rising badge. It lets all traded Pokemon obey you, and you can use the move waterfall to scale them when not battling.
Beat team rocket at mt moon, Pokemon tower, game corner and silph co and get the 7th badge now you can fight the last gym leader.
u get it from blue once you get all eight gym badges in kanto
After defeating Blaine, go to Viridian City and beat Blue.
Mainly Johto, but after you beat the Pokemon League you can go to the Kanto.