Then you must return to Undella Town, and use surf to go to the Seaside Cave on Undella bay. You then head north to Humilau city. Beat an easy gym battle and head west to... Nothing. You meet Colress and catch Terrakion, one of the three Pokemon of Unova. You continue west to find two Plasma grunts. Don't worry, you do not have to fight them, they just tell you to head back to the seaside cave. Explore the cave through its river-route and find a Crustle which you can awaken with your new useless object Colress has given you (I recommend catching this Crab, it is very tough and useful in a fight). Go through the door he was blocking and board the Plasma ship. Take down about 15 grunts (you will have to go back to the seaside cave afterwards so the doctor can restore your Pokemon's health. You now must take down Zinzolin once more, before moving on with your Journey. Hope this helped!