Wall Watcher

Wall Watcher was a boss added in the very first demo of Dream Flash: Demo 1

Base
Wall Watchers move along the edges of the room at a slow pace, firing parallel laser shots and targeted singular big ball shots. In phase 2, they switch to a shotgun pattern of circular bullets and start firing faster.

Green
Green Wall Watcher’s parallel shots will slow down and trail off in a random direction, and it’s ball shots split into four smaller projectiles. In phase 2, it starts firing parallel boomerang shots, which bounce off of the walls.

Orange
Orange Wall Watcher stops moving every few seconds to fire a laser beam forwards. It also fires parallel shots at a much faster rate than the others.

Pink
Pink Wall Watcher fires three ball shots at once. In phase 2, it fires five ball shots at once.

Base
Do NOT go in front of the boss’s guns or in the center of the room, instead move around the edges of the map along the boss’s movement path, slightly in front of the boss in that way.

Green
Same idea, but remember that the green orbs explode into lasers and try to plot out your movement accordingly. The boomerangs are spaced enough to comfortably squeeze between them.

Orange
Again, just follow the same strategy as base watcher and the ray of dooms should miss. If there are two of them, try and estimate where the other one is to avoid its beam as well.

Pink
Keep a bit more distance between you and the watcher to allow for the pink orbs to spread a bit and give yourself more room to dodge them. If there are two, this boss can be tricky, but hug the wall and most of the projectiles should not be a threat, with some getting eaten by the wall itself.

Trivia

 * In the sprites, Wall Watcher is called "Wall Observer" while in Recollection, it is known as "Wall Wanderer." However, it is officially referred to as Wall Watcher in ramaf's notes and that is the name most commonly used
 * Wall Watcher gained knockback immunity after Green Wall Watcher's boomerangs glitched out of the map when knocked back
 * Orange Wall Watcher's lasers were subject to many glitches involving Rubber Soul, Invincibility Frames, Warding Fig, Bullet Eater, and some barrier weapons due to its constant nature