You can get three:
-one in the battle company in castelia city from the janitor on the 1st floor right as you enter the battle company.
-from the Pokemon fan club chairman after you level up a Pokemon 25-49 levels.
-held by the shining Benga's dratini/gible after completing white tree hollow/black skyscraper.
You can get more through cheating or trading but thats all for ingame