You can catch a Ditto in, Route 35, Route 47, Cerulean Cave
You can also choose Torchic from here.
> After beating Red and going to Professor Oak he'll give the option of
> Squirtle, Charmander or Bulbasaur.
> After getting the starter from Professor Oak go to Silph Co. Beside
> the counter on the right is Steven Stone (If you've met him by getting
> the little girl her PokeDoll back) he'll ask what gem you would pick.
> Green is Treecko, Red is Torchic and Blue is Mudkip.
If you want to breed them, go to Route 34 catch a Ditto from the locations I listed above and then get the Torchic if you haven't already, and place them in the Daycare, and bike around, then if you ask the guy outside the daycare he might give you an egg.