School Staff
The staff of Baldi's Basics Plus are the characters who enforce rules, hand out tests or run the shop, and Baldi is the only one whose catch costs a life. These are the adults of the Super Schoolhouse; the students and wandering characters are on the troublemakers page.
Baldi
Baldi hunts by sound and gains speed with failed activities and later floors. His ruler slap is the audible gauge of his speed. If he hears you climb into a locker he pulls you out with his own voiceline, and he does not tag you while speaking.
He unlocks locked doors when passing through them. After the time limit expires he speeds up gradually, and on Levels 4 and 5 his speed curve is steeper than on the school floors.
Principal of the Thing
He sends you to detention for rule breaks such as running in the halls, drinking BSODA where he can see it and opening a storage locker. Each rule break has its own timer before he reacts, and he knocks on faculty room doors a few seconds before entering.
Detention is shown by a timer above the principal's office doors and counts down at 1.25 times normal speed. After the time limit he treats you as guilty on sight and switches off the lights in rooms with finished activities. His raised-hand sprite appears only while he is chasing someone.
Mrs. Pomp
Mrs. Pomp announces a class and expects you to reach it. Her YTP reward depends on how quickly you arrive, and she can drag you to the room. She cannot grab you inside vents, while squished or in an opposite orientation, though she can still invite you.
She unlocks locked doors when passing through them, like Baldi and the principal.
Dr. Reflex
Dr. Reflex wanders and chases you within his line of sight, then gives a reflex test: click the circle icon he raises at random times. Passing earns YTPs, failing costs only time and each test in a floor gets harder or longer.
Walking away mid-test sends him to his examination room for a giant percussion hammer. He then tracks you by sound and squishes any character he meets. Squished players cannot interact with most objects. He cannot hammer anyone inside a vent.
Johnny
Johnny runs Johnny's Store in the Pitstop and sometimes inside floors. He occasionally discounts items, lets you buy once per game while up to 100 YTPs short and comments when you buy or try to buy a restock.
The restock button costs 250 YTPs and replaces every item in the available slots. Prices and stock are covered in the items and YTPs guide.
The Test
Looking at The Test slows time around you. Looking away teleports it to a random hallway cell. Staring too long makes it shake and explode, after which the environment speeds up for a while. It respawns only when a new round starts.
How these characters shape each floor is covered in the Hide & Seek floors guide.