The Ray Gun(レイガン, rei gan) is a long-range weapon used in all three Super Smash Bros games and differs significantly. The green lasers it fires have a high knockback and a medium fire rate.
A Ray Gun can be shot sixteen times before it runs out of ammo. Each shot does minor damage (between 2-4%). One of the better combo weapons, it causes enough knockback to hit a person multiple times, and can even be used to KO at low damages if the shots are timed correctly. One of the available bonuses in Melee is "Laser Marksman", which means every blast from a single gun made contact with an enemy. The Ray Gun's projectiles can be reflected or absorbed, while the gun itself (when thrown) can only be reflected. Like other shooting items in Super Smash Bros. Brawl, characters can move while firing.
Damages in the original
Tilt Up: 8%
Tilt Down: 2%
Smash Up: 12%
Smash Down: 3%
Tilt Up: 10%
Tilt Down: 11%
Smash Up: 10%
Smash Down: 15%
Super Smash Bros. Melee
The Ray Gun is toy-like in appearance and shoots short, fat, highly reflective beams of green light. The gun is fairly weak, but since it fires so fast, it can easily juggle enemies. It contains enough energy for only 16 shots. Try dropping it with a few shots left and watch your foes waste time and energy retrieving it.
Super Smash Bros. 4/99
Super Smash Bros. Brawl
A gun that shoots rays of light, as the name suggests. Its fat shape is not very realistic--in fact, it looks more like a toy than anything else. Its beams aren't very strong; they're fast and hard to dodge. In addition, they juggle whomever they hit in midair, making it possible to hit with one beam after another. By the way, it only holds 16 shots. When it's empty, you can throw it.
Super Smash Bros. 3DS/Wii U
To Be Added
In the original Super Smash Bros., CPU players never fire the gun at Fox or Ness due to the fact those two can reflect and absorb the beams, respectively. They instead throw the gun at them.
The Ray Gun's appearance in Melee (and the original Super Smash Bros.) is very similar to a gun used by the Ray robot in Custom Robo for GameCube. However, since its trophy in Melee reveals that its origin is the Super Smash Bros. series, this may be coincidental.
The Ray Gun in Super Smash Bros. for Nintendo 3DS/Wii U has been redesigned completely. It has a more futuristic design and like the Ray from Brawl, it doesn't have a sight (the thing thats stick out on top of the gun). Also, instead of a trigger it has a button and in front of the muzzle, it has the Smash symbol that appears backward because it acts like a stamp. As Sakurai said in his Miiverse post, they are trying to differentiate between the Ray Gun and an actual gun.