After you pass through Ula'ula Meadow, you reach Route 17 on your way to Po Town.
In the Po Town Police Station, there is a pink sparkle for the Zygarde Cube.
If you go east, you find a slope up to a rocky area. To the left of the top of the slope, there is a hidden X Attack.
Go north up the easternmost path and you will find a Lemonade to the left.
Keep going north, and at the top you can battle a Team Skull Grunt who has a level 34 Golbat. You get 1088 Pokédollars for winning.
Go north through the grass above the Team Skull Grunt to get a Full Heal.
Go to the left from the Team Skull Grunt and jump down the ledge. There are two ledges south of that. If you go down the right-hand ledge, you find a green sparkle for the Zygarde Cube.
From here, if you go down the ledge on the left, you can battle a Team Skull Grunt who has a level 33 Mareanie and a level 34 Fomantis. You get 1088 Pokédollars for winning.
Go down the ledges from there, and if you go south you can battle a Team Skull Grunt who has a level 33 Salandit. You get 1056 Pokédollars for winning.
Go east to go back up the ramp to the rocky area. Go to the top, and this time go down the leftmost ledges. This will lead you to TM84 Poison Jab.
Go down the ledges, then go west, then north. You can battle a Team Skull Grunt who has a level 33 Rattata and a level 34 Raticate. You get 1088 Pokédollars for winning.
To the right of the door to Po Town, there is a hidden Dire Hit on the lamp post.
Go up to the grunts at the door of Po Town and you have to battle them. The Team Skull Grunts have a level 34 Drowzee and level 34 Haunter. You get 2176 Pokédollars for winning.
The Grunts don't let you in, but a mysterious man shows up and lets you into Po Town.