If you mean how do you get into the gym?
you have to beat all of the Rocket goons in sliph co.
If you mean how to get through the teleporters ?
heres a map from soulsilver and heartgold but it also works for leafgreen and firered
http://www.psypokes.com/hgss/gymmaps.php?map=saffrongym
wdwdwstr
in gym durr
no
Brock the rock gym leader
Pewter City
i think it iz erica she uses leaf Pokemon so either use ice or fire Pokemon
You can do the gym leaders in any order you want, although from the Fire Red/Leaf Green point of view the 6th gym leader would be either Misty or Erika.
Poison type pokemon, other trainers in the gym also have psychic but again the leader has poison type
in the city that you find the grass gym leader
Its in virdian city. The gym leader is Govanni, and he uses ground and fighting pokemon.
Giovanni is the leader of team rocket and the 8th gym leader in fire red and leaf green.
leaf