Neo-Ridley (also known as, Ridley-X) is the X-mimicked clone of the Metroid series' antagonist, Ridley. It was mimicked by a Core-X holding the Screw Attack, which cloned the frozen, and probably dead, body of Ridley in Sub-Zero Containment. Ridley's body may have been moved to the B.S.L station from the Bottle Ship along with specimens such as Nightmare. Like Ridley and every other incarnation of the creature, Neo-Ridley proceeds to attack Samus, albeit for the cause of the X and not the Space Pirates.
When Samus enters Sub-Zero Containment from the Main Elevator, Neo-Ridley awakens and leaves as a gelatinous X. Samus leaves the room, only to find Neo-Ridley later in Sector 1 (SRX). Neo-Ridley's attack pattern is familiar, as this particular X within it does not grant Neo-Ridley any special attacks, despite holding the Screw Attack. Curiously, when Samus first encounters the already mimicked form of Ridley in SRX, it sits and appears to be the same carcass as before, despite being healthy enough to move freely.
For the most part, Neo-Ridley's primary attack is to ram into Samus, causing contact damage and taking advantage of its large sprite. It can also fire missiles from its mouth, which home in on Samus and are dodgeable with the Space Jump. The beast may turn to the use of its claws, gripping Samus and inflicting heavy damage over time. It also uses its tail to stab at Samus while she is on the ground.
Neo-Ridley can be damaged by simple shots of Samus's Plasma Beam (yet only when charged), Super Missiles, or Diffusion Missiles. He is unaffected by Samus's other weaponry, including Bombs, Power Bombs, and uncharged Plasma Beam shots. Ridley's tail is invulnerable to any of Samus's weapons. This property of his tail, paired with its length, makes it an effective shield for him throughout their battle.
Upon defeat, Neo-Ridley will transform back into a resilient Core-X. Once the shell of the Core-X is destroyed, Samus can absorb it, regaining her Screw Attack.
- Due to the size of Neo-Ridley's sprite, the Game Boy Advance may lag slightly during the fight.