First you need to get to one island when you get there go towards mt ember and stay in the grass you will eventually find ponyta.
you can't get it from a friend that has firered or leafgreen
in the video game section
No you can only get it at the beginning of the game.
Ponyta is not in the game.
you can't get a shellder in leafgreen, you can only get it in firered. you can ask a friend that has that game to catch you a shellder and trade it to you.
you have to buy a game shark
search it on youtube
in the safari zone or you can buy it at the game corner
you can't only if u have a game shark
you can't CATCH squirtle in leaf green. but it can be chosen as starter Pokemon at the beginning of the game.
you need to start out with bulbasaur at the start of the game, beat the game, get the rainbow pass, encounter then track entei then try to catch it.
You can't catch mew without a ticket. You can get it from gameshark or trade it from another game, but you can't catch it.