Um, you can see Gary in Pokemon Yellow if you name your rival Gary! Also, if you mean where do you find Gary after you've started your journey, go west of route 22(The path west of viridian city) and go north past the grassy area then west until your hero freezes in place and Gary walks over to him, challenging you to a battle you can't refuse. He will have a level 9 Spearow and his level 8 Eevee. You may want to train your Pokemon a bit before fighting him.
Giovanni
hes in the underground base where the slot machines are .there will be one of his grunts up against the wall speak to him
You can't go to Johto in Pokemon FireRed or LeafGreen.
Master ball is with the silph co. chairman talk to him after defeating Giovanni
go through the rocket game corner and defeat Giovanni to get the silph scope, you need to get the lift key in the game corner then go to basement 4 and beat Giovanni.I dont know for firered but i know for leafgreen.
team rocket boss
Giovanni
You go to Saffron City, go to the Silph Co., take out Giovanni, then beat Sabrina
nowhere
Viridian City.
As the gym leader, Giovanni is supposed to be the eighth of them. So you have to beat the other seven before you can get to him.
You use it on the lift (1st Floor) to get access to Giovanni. This is your first battle with Giovanni.
you have to go too Fushia City beat the gym leader then they will let you in Saffron City then go in to Silph Co. and get to the last floor find Giovanni battle Giovanni then then get out of Silph Co. and you can go in the Saffron gym.
I believe you can get it after fighting Giovanni for the last time.
You have to beat Giovanni in the Celadon City Gym.
Rhydon Persian kangaskan And 1 other pokemon that I'm not sure of good luck
Giovanni is the leader of team rocket and the 8th gym leader in fire red and leaf green.