I read that you talk to the guy in the Pokemon center and trade 5 Pokemon from global trade center and I did that but...Instead of giving me a master ball he gave me a...WIDE LENSE...Why?
You get a master ball from professor juniper in castelia city and/or mistralton city. The person who gave you a wide lense will give you different items depending on how many times you trade with gts or gts negotiations.