The wiki is useful for a basic summary. Samus has 18 different beam weapons, 5 different types of missile, 6 different visors, a bunch of movement systems, and 7 different suit upgrades.
Samus in Metroid Fusion (current abilities) has a beam that stacks Power, Wide, Plasma, Wave, and Ice. That's 5 beams in 1, which results in a blast of force (Power), that is 6 feet tall (Wide) and peirces enemies (Plasma), goes through walls (Wave), and freezes things (Ice.)
Her missiles stack Regular, Super, Ice, and Diffusion. 4 missiles in 1. Every missile she fires is 3 times as powerful as a normal missile (Super) and is able to freeze things (Ice.) If she charges it, the missiles blast radius expands to freeze everything within 15 feet (Diffusion.)
Current movement systems include the Speed Booster, Space Jump, and Screw Attack. The Speed Booster lets Samus run at supersonic speeds (at least 768 miles per hour) and surrounds her in a field that just breaks things. The Space Jump lets her somersault continuously in the air, allowing infinite jumps which basically let her fly. The Screw Attack surrounds Samus with an energy field whenever she somersaults (infinite Space Jump = infinite Screw Attack) that damages/destroys anything that she touches.
Current suits are Fusion, Varia, Gravity, and the UAM 1. 4 suits in 1. Each one increases her defenses. Fusion is the normal suit and can absorb X-Parasites that try to infect her. Varia protects from extreme temperatures (hot and cold) as well as acid. Gravity nullifies resistence from liquids and gravity effects, and can let Samus walk around in lava without any problems. UAM 1 is an unnamed suit that resulted when the Fusion suit absorbed the SA-X, which was an X-Parasite mimicking Samus' original Power Suit. So Samus basically aborbed herself, and that pretty much shot her defenses into the stratosphere, since the Fusion suit absorbed the original Power and Varia suits.
I would say so, yes, but I may be biased as the biggest Samus fanboy on this forum. Alex is a powerful opponent, but I don't see him getting past Samus.
Actually, I'm currently considering what would happen if the Fusion suit even came into contact with Alex. Ever since Samus was infused with Metroid cells, she's been able to absorb X-Parasites for health and ammo. X-Parasites are shapeshifting viral organisms that copy the appearance, abilities, and memories of whatever they infect and consume. Alex is a shapeshifting viral organism that copies the appearance, abilities, and memories of whatever he consumes. After killing its host, all Samus had to do was touch an X and she'd consume it, sometimes gaining a new ability in the process.