I'm simply just bored again so I'm going to cover all of the secondary riders that my first ten main riders have.
Kamen Rider Inferno, Gale, Zero, and Tremor
These four riders come from Disaster and at first these guys don't become riders till the middle half. Originally there is the villain named Storm, but when the true god comes forth and gets rid of him he gives three of these riders human bodies and then can use their powers like the main rider does. So the four are villain riders and one changes side when the second villans comes into place. Tremor experiences a change of his powers when he tries to fight the god and his former friends with their new powers. All of these riders have a single element as Inferno is fire, Gale is wind, Zero is ice, and Tremor is earth. Inferno uses an axe and a bow for his main weapons. Gale has a staff, Zero uses hidden weapons like knives and shurikens, then Tremor has a great sword. This then connects to Disaster because he has a similar ability with his form changes to these four other riders. Also for the first villain I did think of making him a rider and calling him Kamen Rider Storm, but for story purposes I didn't have him be one. The same goes for the god known as Disaster, I was thinking of calling him Kamen Rider Calamity. Pretty the main deal with most of the powers in Disaster's world is that they are shared powers because the main story deals with a race of beings.
Kamen Rider Heaven, Aybss, and Kamen Rider Hellfire
These three appear along with Kamen Rider Satan and I want to do a story like Kiva, but actually get things right. Heaven is like IXA, a rider that has to fight with the opposing side. The problem with Kiva it was not well represented well. With Satan and Heaven there is an obvious reason why they fight each other. Heaven follows the words of the angels and Kamen Rider Satan is their number one threat. He is sadly played as a puppet when he appears. At first I thought of the generic bow and arrow concept, but I changed it for something else. I was thinking about Monks in RPG's and they use their fists! So I changed Heaven into the Heavenly Boxer where the arrows are his fist. Heaven also gains a final form called Gateway just like Satan, but it increases the speed and power of his punches and he can materialize energy arrows from his fist. Kamen Rider Aybss is a dark magic rider that uses a magic staff. He originally worked with Hell itself, but escaped and became a wanderer trying to find peace with himself. Kamen Rider Hellfire is then a final villain who appears as he is a stronger version of the main rider's default form. Hellfire's story is that he was a last minute resource to stop the main hero from suceeding as his character was originally a wandering zombie kind of being that got loose from Hell.
Kamen Rider Stardust, Kamen Rider Comet, and Kamen Rider Blackhole
In Kamen Rider Cosmos there are three other riders as the first two are allies and then the last one is a main villain. I will talk about Blackhole first then. He is a leader of bandits that had battles with the Cosmos kingdom before and he tries to attack once more with a new plan. He attacks the king and when he kills him, he takes his sword and powers. With him though the powers change into dark energy to better fit his dark matter powers. Also the sword he takes will soon go to Kamen Rider Cosmos when he achieve his final form. When Blackhole uses the sword he can cut the matter around him to make tiny blackholes where he can suck people in and make them pop out where he wants them to. Originally Kamen Rider Stardust was one of the royal guards for the king, but due to the recent attack he is forced to leave and before he dies, he sends his gun (transformation device) off to the Earth hoping that someone can help the prince. A police officer who wants to help the Cosmos empire ends up finding the gun and learning of the attack through a message from the device. Stardust gains a final form where he can use wires to trap enemies and this is called Constellation form. He can shoot in patterns that represent the different constellations. Kamen Rider Comet is a different race from space that went berserk before the Dark Matter Bandits attacks the kingdom, where the king had to seal him into a passing comet. Blackhole uses this comet and breaks the man free as he goes berserk on Earth. Cosmos helps him gain his sanity back as he remembers the king saving his life because he could have been easily executed for what he did in his past. Comet is a strong brawler type and his final form is called White Comet where he gains higher speed and a bit of fire element.
Kamen Rider Wave and Kamen Rider Absorb
In Kamen Rider Infinite, the main hero helps people that are being killed by strange natural creatures being created by Absorb. Their aims are to steal elemental powers from the people and to make Absorb more powerful so that he can get his human body back. Absorb has a natural look to him along with a bit of mutation as well. His main weapon which is a club, is attached to his body. The club can even change into a claw like weapon. He can also change natural enviroments into what he thinks of. He even finds a way to use people to make monsters by combining them with nature. Kamen Rider Wave is then one of the people that Infinite saves and through long training and mediation, he can summon his elemental powers. He is a water rider that can freely use water for attacks and many other purposes. He can take water from many resources and use them to make slashing attacks with his punches and kicks. The rider can even use water for transportation uses.
Kamen Rider Jewel and Kamen Rider Construction
With Kamen Rider Totem, his story takes place before Infinite's as his villain is Absorb before his sudden change of appearance. Kamen Rider Construction was a man who used alchemy and machinery to improve his city, but at the same time he was forcing it to change. Through alchemy he can create homunculus to do his bidding. He even goes as far to use citizens in these experiments to make stronger ones. He created his own rider armor to defend himself as I took idea from Birth for his weapons. He has a drill, crane, wires, and to change it up a wrecking ball to fight. Kamen Rider Jewel is similar to Totem and Infinited as he gets his powers from the spirits of the Earth as well. Also Jewel will appear in Infinite's story. Jewel worked alongside Totem to take down Construction. Jewel is based on many different crystals like Ruby, Sapphire, Emerald, Diamond, etc. Jewel will have the same amount of forms as Totem as they are the four as mentioned before. Ruby creates a shining effect where he can use solar powers. Sapphire makes his body bigger and stronger. Emerald increases his defenses. Then Diamond is his final form which comes with all previous powers.
Kamen Rider Bullet, Pride, Lust, Envy, Gluttony, Wrath, Sloth, and Dealer
Kamen Rider Greed faces off many foes and at the top of the ranks there are people with belts similar to his. I got this idea when Gaim introduced the Genesis Riders and wanted a force of strong riders for when he gets at the top ten. Dealer originally called himself the new Greed since Greed left the ranked battles. This is how Greed gets his final form from battling this rider. So Dealer has similar powers to Greed's final form. Then the secondary rider is Kamen Rider Bullet who is a mysterious man who wants to get rid of the ranked battles. He always appear in his armor for he is keeping his identity a secret for some reason. Bullet uses a gaunlet weapon where he can perform many attacks with it. It has boosters on it, can actually shoot shotgun rounds, but it's range is not long at all. Bullet has a second gaunlet that can summon the Double form, but it hurts his body everytime he uses it. Kamen Rider Pride is a rider that uses pride as a power. He makes compeitions in his fights and the more he suceeds the more powerful he becomes. His main weapon is a great sword similar to Tremor. Later on, Pride ends up becoming Bullet later on and even combines both systems together to make Prideful Bullet. Wrath is the main villain he is only power is rage. He uses his anger is increase his strength and that it is, he has no weapons, he is an improve fighter that depends on strength alone, but that got him to be number one. Lust uses her desire of love as her strength and she used to be with Greed and Wrath before the story of now so when both are back her powers become much stronger since she sees herself in a struggle and picking which one. She is a fast fighter that depends on her small swords and knives to rack up damage. Gluttony's power makes him a glutton for punishment as he can take damage and redirect it back. Sloth uses his sleep like state as his power where he can make people enter his dreams where he can do whatever he wants. Think of it like the strange dimensions that Metal Hero series loved to use. He has two large claws as his weapon of choice and when someone breaks his sleep state, he goes berserk.
Kamen Rider Data, Virus, Security, Plague, Worm, and Scan
Kamen Rider Circuit deals with computer motifs so many of the other riders will as well. His three allies are Data, Virus, and Security. Data is a dual gun wielding executioner that can combine his guns into one shot gun, think Deka Red pretty much. He gains a final form called Ram where he gets a crossbow weapon and can send energy arrows out and change the rate of fire and the speed. Virus is a sword wielding rider that can use viruses as poison type attacks. His sword is large, but works like a rapier mostly because his style works well with stabbing. Virus gains the Shut Down form which creates a near instant kill attack for him when used properly. Security was originally used by another squad leader, but after being killed the boss of Circuit and the other two takes charge and becomes Security. Security relies on reflective barriers as his main weapon. He can summon then from his hands and can deflect projectiles and can even trap people inside of them. Plague is an out of control villain rider that has a rivalry with Circuit. Both are fast and while Circuit relies on storing energy, Plague focuses on taking energy. He can change his arms into two sharp blades and if he gets direct contact with someone he can take energy from their bodies. Worm is an assassin rider with one trusty sword. He has similar powers to Virus where he can use poision like attacks. Unlike Virus though, his poison cannot kill as it only stuns of weakens his foes. Worm gains the Infected form which gives him more power if he is further infected with a special type of virus. Scan is a rider that uses scanning to his advantage, he usually will stay far away from his foes and point out weakpoints to get the upperhand.
Kamen Rider S.W.A.T and Kamen Rider Berandal
With Kamen Rider Hunter we got a purely good rider and a purely evil rider. Since Hunter starts out more like an anti-hero he has two opposing forces that he has to fight. S.W.A.T is pretty much my version of G3-X. It is heavily police inspired and can be armed to the top with weapons. His standard weapons would be a stun baton and a powerful rifle. Later on he gains better weapons like stronger gauntlets since in the beginning hand to hand combat was not the suit's strongest area. He even gains a tazer like weapon that can reach muh longer than a usual one. Later on he gains the Riot form which gives him two shields on his arms that he can use for both offensive and defensive options. The defense is quite obvious since they are shields, when the two form together they make a much stronger version of the shield. When separated they can still deflect attacks depending on how strong they are. The offensive side of it comes to when they are separated as well since they act like side blades and even if the shield is together as one, it can be used as a great shoving tool. Berandal is literally a thug where his main thing is fighting like a thug. He relies on one weapon, his long knife and relies on his overall power. He focuses on completely destroying his foes as his style of fighting is brutal and would handicap many who fight him.
Kamen Rider V2
With Kamen Rider Prototype most of the people he fights are people aiming to make the completed version of the suit. V2 is a near perfect recreation of Prototype with many improved functions. The big difference is that no man uses the suit, but the suit itself is a robot. For a majority of his appearances he is known as Proto-2 by his creator. V2 gains his own identity and learns about his own independence by the end of the story. Originally though he was made to fight Prototype and destroy the original production of the suit. V2 has the same charging gimmick as Prototype, but V2 focuses on dual weapons. He can equally spread his charges to mutiple weapons at the same time. When V2 gains his new name he also can use the Upgrade form just like Prototype and with his dual weapons makes the form more terrifying than Protoype's version of the final form.
Kamen Rider Realm and Kamen Rider Creator
With Gatekeeper there is other traveler he must worry about and that is Creator. Originally he does not start out as a rider and is just this slime like creatue. He calls himself Creation at this point, but the more he fights with Gatekeeper he starts to get a power he originally lost. Creator is even a big cause of a majority of the supernatural in the many worlds that Gatekeeper travels to since a freak accident happened with the Gatekeeper system, the same accident that destroyed Gatekeeper's world. When he becomes the Creator, he can freely create certains types of things since like Gatekeeper he is connected to the powers of the other worlds. Overall then he was originally another Gatekeeper so when he gains his rider form it is a dark version of Gatekeeper with the gate motif looking rusty and broken along with a broken key blade. Realm can be a traveling rider as well, but for the most part there is one Realm in every world. They defend their worlds from outside powers as some can be good, bad, or neutral. With the outsurge of Gatekeeper then, some go right after him to kill him and end things while others try to help him because of the Gatekeeper system itself. There will be one Realm that gets the main focus and he even fights other Realms, but what makes him stand out is that he gets two versions of his transformation device which is a gaunlet that can use summoning keys. With two together though he becomes the Traveler which is the final form as his powers are increased and can summon up to six riders, originally he could only summon three at a time.
So those are all the riders from the first ten ideas I have thought of. Later on things get more interesting after Gatekeeper as rider powers become worldly bounded unlike most of the previous riders that had completely different powers in comparison to the other worlds.