Seen in “The Greatest Villain”.
Beck the Great RX3 was commissioned by Beck, with the purpose of finally defeating Roger and Big O, and constructed by Yoshifura-Yakamoto Industries, in a ploy for lucrative contracts with the Paradigm Corporation.
Piloted by Beck and his two henchmen, Dove and T-Bone, 3 vehicles combine into the giant robot. The combination sequence is started by the command "Final Together" or "Implement Final Formation!"
T-Bone's trailer transforms into RX3's lower body, the blue vehicle performs a bootleg turn to form the legs and waist. Dove's construction vehicle is the upper body, pulling itself up onto the blue lower half. The torso creates hands from a drill and a pincer. Beck's sports car jumps off a nearby ramp and dives into a recess in the head to form the cockpit.
After this display of bravado and overly-dramatic poses, Roger and Big O destroyed the RX3 in a single blast of O Thunder, ending the fight before it began. The only weapon the RX3 appeared to have was a boomerang-shaped bladed weapon, made by combining the 2 halves of it stored on the shoulders. When combined, the kanji for "cut" appears on the center of the weapon.