Samus is ranked 14th on the tier list. Samus has the longest non-projectile range in the game with her machine gun attacks. These attacks also double as Samus' instant-KO moves, giving her some of the best KO options in the game. She has good close range options, as her Morph Ball has the smallest hitbox out of all the rolling moves and her Screw Attack allows her to deal damage when jumping.
However, Samus' machine gun attacks erroneously increase her hurtboxes to ridiculous sizes, allowing enemies to hurt her by attacking the beam instead. All three of these attacks also have a long cooldown time shared between them, preventing her from using half of her moveset until it expires. In addition, her Power Beam attack is overall lackluster and has a slow firing rate. Her mobility is only average at best as she can be difficult to control when turning since her sprite is not centered properly.
Samus' pros slightly overshadow her cons, allowing her to rank in the higher mid tier.
Samus fires with her arm cannon a fast-travelling Charge Shot, able to damage multiple opponents at once. Though Samus does not recoil from the shot, she visually curls and spins around once every time she fires.
Samus rapidly fires multiple shots in a similar way to a machine gun. Oddly for attacks in SSF, this attack notably has a bit of ending lag, leaving Samus unable to perform any other attack (except for jumping) and rendering her vulnerable. Presumably left over from when Samus was a normal enemy, this is not based on any attack she is known to have. Notorious for the projectile having a hurtbox of its own.
Samus has an additional attack by jumping: she uses the Screw Attack, somersaulting in the air, surrounded in a greenish electric field.
Samus is one of the only two playable characters in the original Super Smash Flash Demo, the other being Blade. It's likely that she was programmed over other unknown data left over from when SSF was going to be a platform game, as she's scaled down to match Blade's height and is referred to in the debug indicators as "Enemy". She also had a significantly faster rate of fire in the demo, which was toned down later on to be less overpowered.
Samus's sprites are not of Samus at all, but of the SA-X, a clone of her that appears in Metroid Fusion which was born from removed pieces of her armor infected by the lethal, intelligent X Parasite.