The Sunriser is RX's transformation belt that is actually the King Stone. The King Stone was split in half and is able to communicate to him telepathically and use sunlight to power RX up. That factor places RX at a disadvantage while in an area that has no sunlight. The Sunriser also allows for Form Change, changing its design to suit the form.
Instead of a Rider Kick, RX used a lightsaber to finish off his opponents. He had a lightsaber called Revolcane, which could be summon from his belt and he would thrust it into monsters before they finally exploded.
Vortech Shooter
RoboRider's signature weapon is the Vortech Shooter pistol that is formed from the right side of his body. It can shoot a powerful solar blast that can destroy an enemy in one blow in the Hard Shot attack. As it is powered by sunlight, this gun ranges limitless and never misses the target.
Bio Blade
BioRider's signature weapon is the Bio Blade, formed from the left side of his body. Like the Revolcane, Bio Blade has also a light saber mode that can slash his enemy in one blow in his Spark Cutter attack.
RX Jump
A name given for an extra powerful jump. RX only shouted it out in episode 42 and in his movie, Sekai ni Kakeru.
RX Kick
Although its no longer a killer move, RX still had a Rider Kick, which was renamed RX Kick. The RX Kick was a double-foot kick.
Kingstone Flash
In episode 40, RX used his Kingstone Flash to reveal a couple of Crisis henchmen. It was only executed in episodes 40 and 42.
Macro Eye
RX used his Macro Eye ability to find out his opponents' weaknesses. Also used to see hidden objects or people behind any obstacles.
Robo Punch
In episode 30, we would get to see the only time when Roborider executed an extra powerful Rider/Robo Punch. As the Prince Of Flames, he got energy from the fire around him and his right hand gave out a strong force of light before punching a Crisis monster.
Changing his size
In episode 45, Biorider managed to shrink himself and get inside Granzairus, a tough monster which was hard to defeat by the previous Kamen Riders. When Biorider was already inside the monster, he destroyed the systems and Granzairus blew up eventually. When it was destroyed, Biorider escaped using the next ability.
Changing into liquid energy
Biorider could change his physical form and turned into liquid energy. With this, he could easily escape from any danger. He could also perform the 'Bio Attack' as seen in episode 22 where he would beat up his opponent in his liquid form. Another advantage when in this form was that he could silently pass through any surfaces such as walls without having to destroy them.
Elastic Organs
In episode 35, Crisis was so close in trying to kill RX. They managed to place a Kaiman Senshi inside RX to kill him from within. They also thought that they had managed to kill him. But unknown to them, when the monster was attacking his heart, RX had transformed into Biorider. What happened was that his internal organs had turned elastic. With that, the attacks had no effect at all.
Merging with another person
Biorider could merge with another individual. In episode 36, Biorider merged with an athlete to help him fight a Crisis Kaiman Senshi in a disguise. As a result, the athlete could give a very strong punch, equivalent to that of an RX Punch.
Producing an anti-toxin
In episode 18, Crisis was poisoning people. Kotaro let himself get poisoned so that he could make use of his Biorider form to convert the poison in his body into an anti-toxin.
Using running water to transform
In episode 45, monster Granzairus gave RX and even the ten senior Riders a hard time. Not even Roborider could handle the monster. Kotaro requested that Kyoko used her telekinetic powers to give him some water from underground. As soon as water gushed out from the crack on the ground, Kotaro stood near it, got some energy and directly transformed into Biorider.
Series:  Kamen Rider Black RX