Question: what to do after you beat team galactic at lake verity?
Answer: After Jupiter and all the Galactic Grunts flee from Lake Verity, Professor Rowan asks you to see if Barry is OK. You must head to Lake Acuity, the lake located at the northernmost point of Sinnoh Region. First Fly to either Eterna City or Celestic Town, then enter Mt. Coronet.