Sector Z was a playable stage in the orginal Super Smash Bros. Although it did not appear in Super Smash Bros. Melee, a similar stage, dubbed Corneria, did.
Differences between Sector Z and Corneria
The differences between Sector Z and Corneria are:
The Great Fox is scaled down in size
You can now stand on the ship's main guns, but can be shot by them too
Pikachu's Thunder Jolt will now go down the ridge of the ship
The Arwings will now come at you from the back of the screen as opposed to just from the side