After you pass through Diglett's Tunnel and Route 9, you can look for Kahuna Olivia in Konikoni City.
Explore Konikoni
In the Konikoni Pokémon Center, there is a man from the Aether Foundation who asks you to catch a Natu. If you show him your Pokédex afterward, he will pay you.
Olivia's shop is across from the Pokémon Center. When you go inside, Olivia's Probopass gives you a letter. Olivia asks you to go through Memorial Hill to meet her at the Ruins of Life. Then Probopass gives you a Max Potion.
At Olivia's shop you can get fossils, evolution stones, and accessories. The woman selling the fossils makes it sound like you can only choose one, but you can actually get all of them. You just can't get more than one of the same type. Each one costs 7000 Pokédollars. You can take the fossils to the Fossil Restoration Center on Route 8 to have them turned into pokémon.
The hiker next to the Photo Club building is one of the Dittos that the police officer in Route 9 is looking for. Try to catch it if you can, because it has good stat bonuses and a good Nature. Afterward, the Herb Seller that the Ditto was impersonating will return, and you can buy herbs from him. Afterward, talk to the police officer in Route 9 to get 16000 Pokédollars.
Talk to the police officer again to find out where the next Ditto is: the Konikoni City restaurant. Talk to the chef behind the counter of the restaurant and answer with "...tto?" to battle the Ditto. Be sure to catch it, because it has good stat bonuses and a good Nature. Afterward, the real chef will return. Talk to the police officer behind the desk of the Route 9 police station to get 20000 Pokédollars.
Talk to the police officer again and you find out that a Ditto is impersonating the masseuse. She is next to the incense seller in the southern part of town. Talk to her and answer with "...tto?" to battle the Ditto. Be sure to catch it, because it has good stat bonuses and a good Nature. Afterward, the real masseuse will return. Talk to the police officer behind the desk of the Route 9 police station to get 24000 Pokédollars.
Talk to the police officer again and he mentions that Olivia is often looking out at the sea. Go to Lighthouse Point in the north part of Konikoni City to find Olivia. Talk to her to discover that this is the fifth Ditto. Answer with "...tto?" to battle the Ditto. Be sure to catch it, because it has good stat bonuses and a good Nature. Talk to the police officer behind the desk of the Route 9 police station to get 28000 Pokédollars. He also gives you a Focus Band.
Go to Lighthouse Point in the northwest part of town and talk to the girl. She wants to see a pokémon from the Alola region that has curly hair. Show her an Alolan Dugtrio, which evolves from Alolan Diglett at level 26. The girl gives you a Dire Hit. She will leave, but if you leave the area and come back, you can talk to the girl again. If your character has Honey Blonde hair, the girl will give you Soft Sand.
Check behind the bench behind that girl to find an Eviolite.
In the west part of town, you can talk to the man near the pier and agree to help him. You will battle Office Worker Dugal. Be sure to use a Z Move during the battle. He has a level 23 Clamperl. You get 920 Pokédollars for winning. If you used a Z Move during the battle, he will give you a Max Revive afterward.
After you are done exploring, go southeast to Route 9, and southeast from there to reach Memorial Hill.