In Celadon City, your rival is Erika.
The fourth gym at Pokemon fire red is grass type gym
You cannot rebattle Gym Leaders.
after you beat the fire gym then walk out and your rival will give it to you.
fire
charizard
You go to saffron city
In Celadon City, your rival is Erika.
Koga's Pokemon are: Koffing Muk Koffing Weezing
In Saffron City, the top right there are two gym looking buildings. The one on the right, I believe is the gym.
no
In his Gym in Cinnabar.
it is in saffron
beat the gym leader
the thunder gym in in vermillion city
In the cinnibar island gym.
You have to beat the 2nd gym.