Eh, either way, it's debatable. There are a large number of situations where Samus' Screw Attack cuts right through attacks, and a handful of examples where it doesn't. Plus, the whole "Cloud has beaten bosses, therefore he's stronger" argument doesn't really do much for me. Remember, those were all team efforts, never single-combat.

I'm going to post all of Samus' abilities just for those who are unaware.

Beam Types/Charged Effect

Power Beam - Rapid fire energy projectile/Super charged blast, equal in power to a single missile.
Wave Beam - Electrical Projectile, can be fired through walls and has homing capabilities/Paralyzes target on contact.
Ice Beam - Slow firing ball of supercooled energy, freezes enemy on contact/Freezes any creature on. contact regardless of their strength.
Spazer Beam - Multi-beam blast/wider blast pattern.
Plasma Beam 1 - Powerful ray of green energy, passes through multiple targets before dispersing/Super charged ray, higher speed.
Plasma Beam 2 - Superheated plasma ray, incinerates most enemies on contact/Super charged plasma blast, capable of incinerating multiple targets at once.
Phazon Beam - Easily Samus' most powerful weapon. A constant stream of destructive blue Phazon energy. Can only be used when Samus is standing in a Phazon Pool. Considering that this fight does not take place on Tallon 4, there's not really any way she could use this beam.

Beam-Missile Combo Attacks - All of these attacks require missiles to be spent.

Super Missile - Power Beam enhanced missile blast. Either twice or thrice as powerful as a standard missile. 1 missile.
Shock Cannon (I think that's what it's called) - A constant stream of electrical energy. Think of a Proton Pack from Ghostbusters. I missile per second.
Ice Spreader - Ice Beam enhanced missile blast. A thick sheet of ice spreads across everything for a 10 foot radius, freezing anything in it's path solid. 1 missile.
Flamethrower - A constant stream of scorching plasma. Think Proton Pack with molten lava. 1 missile per second.

Beam-Power Bomb Combo Attacks - All attacks listed cost one power bomb

Charge Bomb - A quick burst of pure energy that surrounds Samus.
Wave Bomb - A criss-crossing pattern of wave energy streams.
Ice Bomb - A shield of whirling ice energy that protects Samus from harm and freezes any that touch it.
Spazer Bomb - A criss-crossing pattern of Spazer streams.
Plasma Bomb - A large plasma explosion surrounding Samus.

Extra Weapons

Missiles - Equal in power to a charged Power Beam blast. Finite supply. Can be fired rapidly.
Super Missiles - Different from the type mentioned above. Either twice or thrice as powerful as normal missiles. They travel at a much faster rate than normal missiles. Cannot be fired rapidly.
Power Bombs - Can only be used when Samus is in Morph Ball form. Creates an expanding dome of destructive energy.
Grappling Beam - Allows Samus to latch onto certain surfaces and swing. Can be used as a low-damage weapon.

Visors

Standard Visor - Displays all suit status in a heads-up display.
Scanner Visor - Scans any lifeform for biological specifics and weaknesses. Instantly downloads all data directly into Samus' brain.
Thermographic Visor - Infrared vision. Simple as that.
X-Ray Visor - X-Ray vision.

Suit Upgrades

Power Suit - Standard Chozo Armor. Compatible with all additional weapons and enhancements.
Varia Suit - Capable of withstanding intense temperatures, increased shield strength over the Power Suit.
Gravity Suit - Submersion in water and other dense liquids has no effect on Samus' speed, maneuverability or mobility. It's as though the water isn't even there. Increased shield strength over the Varia Suit.
Phazon Suit - This one could be debatable. Increased shield strength over Gravity Suit. When Samus is near a Phazon deposit, she can use the material to power her Phazon Beam, which is easily the most powerful weapon in her arsenal. Considering that the arena is not located on Tallon 4, there's little chance the Phazon Beam could be used in this fight.

Movement Upgrades

High Jump Boots - Doubles Samus' jump height.
Speed Boots - Allows Samus to run at a blinding speed. While Speed Boosting, she is nearly invulnerable to attacks from enemies and can dash through rock walls and other barriers.
Space Jump - Allows Samus to stay airborne for an unlimited period of time.
Screw Attack - Surrounds Samus in a cocoon of pure energy, allowing her to destroy obstacles, kill enemies and deflect nearly all attacks from enemies as long as she's airborne. Combined with the Space Jump, she's nearly untouchable.

Morph Ball Upgrades

Morph Ball - Samus rolls up into a metallic sphere, slightly larger than a basketball. While in this form, she has increased mobility and ground speed, and becomes a smaller (and therefore more difficult) target.
Bombs - Compact orbs of low-power, explosive energy. Samus has an unlimited supply. She can also use them to propel herself upwards through the air without taking any damage.
Spring Ball - Allows Samus to jump while in ball form. High Jump, Space Jump and Screw Attack abilities can not be used in Morph Ball form.
Spider Ball - Allows Samus to magnetically attach herself to any surface while in Morph Ball form. She can roll across ceilings and walls with this ability.
Boost Ball - Allows Samus to charge her Morph Ball with energy and use it to gain a boost of speed.

And that's basically all that I can remember. If anyone sees anything that I forgot, then please include it. Keep in mind, I've mainly listed weapons and abilities that she had access to in Super Metroid and Metroid Prime. I've only played a minor amount of the first two games, and have included the abilities that I can remember from those games. I haven't touched Metroid Fusion, so if anyone has further insight on that game, it would be appreciated.