After you reach Seafolk Village on Poni Island, you and Lillie make your way north to Poni Wilds.
Poni Wilds are north of the Seafolk Village. From where you enter Poni Wilds, go west to reach Poni Beach.
There is a hidden Pearl in front of the rock near the surfer.
There is a hidden Big Pearl behind the sign.
There is another hidden Big Pearl to the north.
North of that, there is a Max Repel.
Explore Poni Wilds
Go east from the beach, then go north and talk to the Ace Trainer. You can talk to him for an optional battle. Ace Trainer Elwood has a level 45 Tropius and a level 46 Lilligant. You get 3128 Pokédollars for winning.
North of the beach, on a cliff, you can have a double battle with Capoeira Couple Cara and Douglas. They have a level 45 Mienfoo and a level 44 Mienfoo. You get 3200 Pokédollars for winning.
East of the couple, there is a Rare Candy.
North of the Seafolk Village entrance, you can battle Ace Trainer Lindsey. She has a level 45 Garbodor and a level 46 Toxapex. You get 3128 Pokédollars for winning.
To the north, there is a tree where you can get some berries, and east of that tree, beyond a patch of grass, you can battle Ace Trainer Kekoa. He has a level 45 Granbull, a level 45 Sharpedo, and a level 46 Ampharos. You get 3128 Pokédollars for winning.
East of the Ace Trainer, beyond a patch of grass, there is a Max Potion.
Go south from there, through the grass, until you reach a short ramp on the left that leads to a Dusk Stone.
Go east, and you can go north to find a tree where you can get berries.
To the south, you can battle Cook Fil. He has a level 44 Exeggcute and a level 44 Ribombee. You get 1760 Pokédollars for winning.
If you have defeated all of the trainers in this route, you can talk to the Dancer near the entrance to Seafolk Village for an optional battle. Dancer Julia has a level 46 Baile Style Oricorio, a level 46 Pom-Pom Style Oricorio, a level 46 Pa'u Style Oricorio, and a level 46 Sensu Style Oricorio. You get 1840 Pokédollars for winning. You get a Focus Sash after the battle.
Go south from the Cook to reach Ancient Poni Path.