Under normal circumstances and excluding trading, breeding, and cheating, you can only get one starter per game. Some games offer you a second starter after you've cleared most of the game, but they're from another generation. The same applies for any additional starters. In short, ONLY ONE.
Answer In order to get a Shiny Charizard on Pokemon: Fire Red, the way I did it is reload the game over and over until you get a shiny Charmander. It takes many times because the chances are very low, save in front of charmander where you pick your starter and prepare for many resets like over 1000 tries.
The starter that you pick at the beginning of any Pokemon game is your first starter. So unless you're hacking, you won't have any Pokemon before you select your starter.
Just two, Pal Park and the starter you get in the game.
you can get shiny Pokemon by using your diamond/pearl game to chain Pokemon you can use your poktech to keep track of the number of Pokemon your catch. depending on how many you catch you should evetually get a shiny, or just get really really really really super duper extra lucky and run into one, but i recomend chaining. your go to gameradar and type in shiny Pokemon or Pokemon diamond/pearl how to chain Pokemon.
to create something further to do in the game, and to create more rarities. there are many answers.
it takes a while depending on what game ex. diamond 20 - 30 tries. an easier way is to get a action replay code and you can make it shiny
You can find 2. Route 6, and Dragonspiral Tower.
You can only ever have one starter in any game (unless you cheat)
1 starter pokemon.
YOU DON'T REALLY LOOK FOR SHINY POKEMON YOU JUST WALK AROUND IN TALL GRASS (OR ANY OTHER SPOT TO CATCH POKEMON) AND THEN OUT OF THE BLUE A SHINY POKEMON APEARS.
In my opinion, Snivy is the best, but in the game there are not many fire type pokemon, so tepig may be rarer.
it could go on and on. have to be lucky