Diglett Tunnel

Walkthrough: After finishing your Trial, Kukui will ask that you meet him at the Dimensional Research Lab. Here, you will meet his wife, Brunet, and learn more about Cosmog's past and Ultra Beasts. Apparently, there are these Pokemon that live in other dimensions, ones of great strength called Ultra Beasts. Cosmog may be very weak, but it's actually able to summon wormholes to and from these dimensions.

After explaining this, Burnet will then tell you how Lillie was taken through one of these portals and ended up on a beach a few months prior, living with Kukui and Burnet ever since. After all of this has been told to you, you will then head to Diglett Cave in hopes of getting to your Grand Trial and the Ruins on the other side of the island. Diglett Tunnel is just south of Heahea City. Within Diglett Cave, you will meet more people from the organization called Aether, as well as have to team up with Hau to again Battle Team Skull.

Wild Pokemon:

Walking (Levels 19-22): Zubat(70%), Diglett(30%)

Rustling Spots (Levels 19-22): Diglett(100%)

Zygarde Cells: There is one Zygarde Cell found here.

Trainers:

Worker Frank - Level 22 Diglett

Worker Vaclav - Level 22 Machop

Team Skull Grunts - Level 22 Salandit, Level 22 Formantis

Worker Jeff - Level 21 Roggenrola, Level 22 Mudbray

Black Belt Greg - Level 23 Hariyama

Items:

Dusk Ball - Near Worker Frank

Fire Stone - Northwest Tunnel

Hyper Potion - Halfway Through The Tunnel

Max Ether - From Hau

Max Revive - From Black Belt Greg