Boss 11: Nightmare

Use Sense Move to dodge gravity-spheres and build charge; fire your regular beam otherwise.

Dodge Nightmare's spinning lasers with the Space Jump.

When Nightmare is low on health, the timing for dodging lasers becomes more strict: position yourself between beams, Space Jump briefly, land, and prepare to jump over the next.

Run clockwise or counter-clockwise depending on the laser sweep direction.

Your beam will freeze the gravity device on Nightmare's tail.

Once the device is frozen, fire three Super Missiles at its face.

When the camera zooms in, use Concentrate or Search View (a mode to scan the environment) to fire your Plasma Beam until autoaim is acquired in Normal View (when its tail lights up).

Avoid Nightmare crawling on your platform by hugging the wall and using Space Jump, or by Space Jumping off the platform until you can return.

Do not fall to lower levels, as this wastes time and gives Nightmare an advantage.

Utilize the View Trick, Fast and Instant Super Missiles during this fight for an easier experience.

Freeze the device again and fire more Super Missiles until its mask shatters.

Take the door at the top of the room.

Go down the path and take the elevator to Sector 0.

Save at the Navigation Booth (a save point).

Go straight down the path.

When forced into Search View, look left. A cutscene (an in-game cinematic) starts.

Run all the way back and disregard the Zebesians (enemies).

When the vacuum of space appears, run towards it.

Before Samus is sucked into outer space, she activates the Gravity Feature.

Continue to run straight to be safe.

Save if desired.

When you return to Sector 2, run straight then Shinespark (a charged dash move) left.

Go into the room where you fought Nightmare.

Drop down and try to walk into the door.

Nightmare will stop you again.