Emboar is a new fire type pokemon in Pokemon Black and White. Emboar evolves from a Pignite at level 36, which evolves from a Tepig at level 17.
Emboar is only attainable from evolving the starter pokemon Tepig into Pignite, and then into Emboar, none of which can not be caught in the wild.
If you want all three starter pokemon and their evolutions, you’ll need to get to the first pokemon center where you can trade pokemon. Trade your starter, then restart your game. Do this process twice picking different pokemon. On your third restart, have all of your starter pokemon traded back and you’ll have all three starter pokemon.