Heres how you beet the team galactac grunts in vielstone city. first you have to beet maylene, the citys gym leader( machoke lv.27, meditite lv.and Lucario lv.30.) then Go out of the gym, and dawn/duncan will come up to you and tell you that he/she lost his/her pokedex. then you have to go to the gruntswith dawn and the two of you will batte the grunts.