Once you beat the game, go back to sunnyshore city and talk to the old people that say that once there was a friendly boy in the town named cyrus (team galactic boss)little do you know they are his grandparents and go everyday until you see cyrus. he will ask you if you want to join team galactic. If you say yes, than you only do one mission-rob the pokemon department store but then you will never be able to go in there again.