Details: Should you go to Big Wave Beach, a youngster there will mention some weird happenings occurring at the Trainer School back on Route 1. If you go there at night, a girl with a Drifloon will speak to you about seven mysteries that are happening in the school. Should you need help, the girl will even give you various hints on how to solve the mysteries.
The Mysteries Include:
1) Scary PA System - The Speaker On The Upstairs Floor Is Broken
2) Stairs To Nowhere - Interact With The Noticeboard To Find Gastly Cycling The Stairs
3) Lord Slimy - The Slimy Sound Is The Janitor's Grimer Upstairs
4) Scary Lights - A Girl Is Burning Things In The Northeastern Incinerator
5) Cursed Diary - Interact With The Diary On The Shelf To Be Attacked By A Drifloon
6) Ghost Class - The Upstairs Class Of Children Is A Hypno Hallucination
After figuring out those six mysteries, the girl outside will mention how she can't help with the seventh and final mystery. However, she will mention how she moved to The Alola Region without knowing English, noting how she now hopes to protect the school. You will then receive a pair of Wide Glasses, directly before a security guard appears. After he does, the girl, who was the seventh mystery all along, disappears.