After many battles and events in Aether Paradise, you arrive in Seafolk Village on Poni Island.
Explore the Village
Go north to find Lillie. There will be a brief cut scene.
To the left, there is a floating restaurant. You can eat Z-Noodles there. You will get a bonus item after you eat there.
Exit the restaurant and go south to a floating shop on a boat that is shaped like two Huntails. Go inside and talk to the guy to get a Magmarizer and Electirizer. Talk to the Ace Trainer in the shop to get Aerodactyl.
Go east from there, into the Steelix-shaped boat, and talk to the Rising Star in the east part of the boat. She asks if you are a lucky person. She will give you a Lucky Punch.
To the right, the Veteran says that she will reward you if you catch an Alolan Raichu and show her your Pokédex.
Go south from there, and go to the right to get TM91 Flash Cannon. There is a fishing spot below.
Go back outside, and go to the northeast part of town, where you find a Veteran named Kumu who will trade you her Shellos if you trade her a Granbull. You can find Granbull in the grass to the north.
Go north and you reach the Poni Wilds.