When you get back to Olivine City, head straight-away for the Pokemon Center there, and make sure your party is fully healed. Then, head to the lighthouse on the eastern side of town. With the Secret ...

This city hosts the usual assortment of Poke Center, Poke Mart and Gym, but the Gym Leader is not there. She's in the Lighthouse in the southeast corner of town. On your way down there, stop by a few ...