Model O

Omega - 'The Devil Reploid' and 'The False Mega Man'

History
Model O is a mysterious Biometal which origin is unknown. It's believed it was created around the same time as the Model W's that formed from the pieces of Ragnarok. The data of Omega from Weil's memories probably formed Biometal Model O as a strange stone, presumably so because it was near the Model W Core. Model O itself is shaped like the greek letter, Omega (Ω). No artwork of the Biometal Model O was made, only its sprites in the game.

After defeating Omega Zero or the eight bosses from the previous Zero games in Area N, Vent/Aile obtained a strange stone. In the Guardian Base, Fleuve discovered that it's energy properties were similar enough to those of the other Biometal fragments for the character to Megamerge with it. Upon use, the player will instantly resemble Omega in the upgraded form of Zero's old body.

Model O is not a significant part of the ZX storyline. Also, game art for OX Vent and OX Aile seems to portray them with sinister gestures (Vent appears to be laughing wildly or screaming in a beserker state, slightly similar to Prometheus, while Aile appears to resemble Pandora in her position), probably referencing that this Biometal was used by a Reploid with a corrupted data file or a possible chance that there is a small remnant of the Dark Elf in Model O since Omega absorbed the Dark Elf in Mega Man Zero 3.

Power and Abilities
Model OX's movements are the same as those of Zero in the Mega Man Zero series, with the weapons the OX-Buster and the OX-Saber (the OX-Saber used by the player seems is violet-colored, instead of pink saber used by Omega, and its charged saber attack inflicts more damage than Model ZX's charged saber attack), but the ability of Model OX is its infinite Overdrive, which is used to perform a series of techniques that were used by Omega at the end of Mega Man Zero 3; however, the player cannot use the 7-hit combo used by Omega Zero.

OX-Saber Overdrive

 * Arc Blade: An ice projectile attack shot in eight directions, combined with Kuuenzan
 * Ryuuenjin: A fire-based jumping uppercut from Mega Man X4. and
 * Shinkuujin: The thunder-type, crescent-shaped wave of energy from the saber.

OX-Buster Overdrive

 * Instant Level-1 charge shots.
 * Double Level-2 charge shots (perform the Shinkuujin after this to perform Zero's Buster Combo).
 * Earth Gaizer: An attack used by Zero in Mega Man X2, Mega Man Xtreme, and Mega Man Xtreme 2, that involves punching the ground to spit up multiple boulders.
 * Messenkou: Zero's Giga Attack from Mega Man X5 in which powerful plasma bolts erupt from a point where the ground is punched, though the color of the projectiles make it look more like the Rakuhouha from X4).
 * Rekkouha: Zero's Mega Man X6 Giga Attack, which has mighty bolts of light summoned from the sky and ground.

Zero's Retsuzan, Kuuenzan, and Ganzanha are also available for the OX-Saber. Model OX seems to also possess semi-aquatic abilities as the user's speed remains unaffected when submerged. It is one of the most powerful Biometal in the Mega Man ZX series.