It differs from game to game.
In Pokemon Red/Blue/Yellow after you defeat Misty and travel through to the bike shop. They are at first too expensive, but after you reach Vermilion City and talk to the Chairman of the Pokemon Fan Club (ask him to show you his Pokemon), he'll give you a bike voucher. Then you travel back to the bike shop and you can purchase a bike.
In Pokemon Ruby/Sapphire/Emerald it's much easier. You just get to Mauville City and go to the bike shop and the man who owns the place is very generous, so he gives you a free bike. You have to choose between the Acro bike (can do jumps and bunny hops) and the Mach bike (can travel better in the desert and rides very fast) but you can swap between the two bikes whenever you like by just going back to the bike shop and speaking to the owner again.
Gold/Silver/Crystal is basically the same, you just find the bike shop and the guy will give you a free bike.
Pearl/Diamond the bike is in Eterna City. Again just talk to the man and you get it free.
Hope that helps!!
Chat with our AI personalities
Go to Vermilion City, go to the Pokemon Fan Club, talk to the chairman, and he'll give you a Bike Voucher. Go to Cerulean City, to the bike shop, talk to the guy at the counter, and he'll give you a bike.
You have to get a Bike Voucher from the chairman of the Pokémon Fan Club in Vermillion City. The Pokémon Fan Club will be the building with the green roof. The chairman will be on the very top left of the table inside. Talk to him and he will eventually give it to you. Then go back to Cerulean City and go to the bike shop and exchange the Bike Voucher for a bike. Have fun with Pokémon Leaf Green Version.
To get the Bicycle you must complete certain objectives: You must reach Cerulean City which is located east of Pewter City you must travel through Mt Moon in order to reach the route west of Cerulean City. Once in Cerulean City go north to Route 24 and defeat all the Nugget Bridge trainers then head east to Route 25 keep going east until you reach a house and go inside. Speak to the pokemon inside and it will talk back to you pleading you to check the PC nearby after it enters a machine, comply with it's request and a human will appear he will tell you he's the famous Bill who set up the PC box system used throughout the Pokemon Center's and for your efforts he will give you a special ticket which lets you board the SS Anne in Vermilion City. Go south back to Cerulean City and go inside the house right above the Gym and go into the hole like entrance in the back to find a Rocket Grunt defeat him to receive the TM Dig then continue going south until you reach a building and a smaller building next to it go inside the smaller building this leads you to an Underground Path that goes to Vermilion City. After you exit you will be on the Route directly above Vermilion City continue going south defeating the trainers on your way and the city will be right below you now you must enter the Pokemon Fan Club located below the Pokemon Center and to the left it will have a green roof and a sign near it, go inside it. Talk to the Gentleman in the big chair and he will request you listen to a story say YES and he will rant about his Rapidash after awhile he will give you a Bike Voucher when you get this go all the way back to Cerulean City and find the Bike Shop which is located directly left from the Pokemon Mart inside the shop show the voucher to the cashier for a free Bike!
You can't.
All starters, including Bulbasaur, can't be caught in Pokemon LeafGreen.
If you trade Pokemon between leafgreen and ruby ruby will have your leafgreen Pokemon and leafgreen will have the ruby Pokemon both in the party they will not be sent to the PC unless you personally walk to the PC and do so.
No.
no