Arm Cannon
Samus's primary weapon, capable of firing energy shots. It has unlimited ammunition and is effective against most basic enemies. It can be upgraded with various beam enhancements.
Missiles
Powerful projectiles that deal significant damage to Metroids and can open Missile Blocks. Limited in quantity, so use them strategically. Missile Expansions increase your maximum capacity.
Charge Beam
Allows Samus to hold down the B button to charge her Arm Cannon for a more powerful shot. This charged shot can also destroy certain blocks and is effective against tougher enemies.
Ice Beam
Replaces your standard beam. Freezes enemies on contact, allowing Samus to use them as platforms or to bypass them. Essential for dealing with certain Metroid forms.
Spazer Beam
Fires three parallel beams, increasing your attack spread and damage. Very effective against multiple enemies or large targets. Stacks with the Charge Beam.
Plasma Beam
The most powerful beam upgrade. Fires a piercing shot that passes through enemies and some obstacles, dealing immense damage. Stacks with the Charge Beam and Spazer Beam (though visually it overrides Spazer).
Power Bombs
Devastating explosives that clear the screen of most enemies and destroy special Power Bomb Blocks. Very limited in quantity, used for specific puzzles and boss strategies. Power Bomb Expansions increase your maximum capacity.
Screw Attack
When active during a jump, Samus becomes invulnerable and damages any enemy she touches. Also destroys certain blocks. The ultimate offensive and defensive upgrade.