Hero Wars: Riders vs. Rangers is a crossover between Power Rangers and numerous Rider adaptaions. This film unites the majorities of both the Power Rangers and all of the Adaptaion Riders. The protagonists of Power Rangers Super Megaforce and Kamen Rider DCD are primarily featured, but the casts of Astro Rider, Power Rider, and Power Rangers: GB also had a supporting role.
The Astro Rider Club discovers that a new Armada fleet is moving towards Earth, led by Captain Marvelous as their Great Emperor. With many revived Power Ranger villains under his command, Captain Marvelous plans to obtain the Grand Power of the Kamen Riders to gain the "Ultimate Treasure in the Universe". Meanwhile, Kit Taylor becomes the Great Leader of a group called Great-Valkyrie Empire and recruits past enemies of the many Riders to take down the Power Ranger teams. Unknown to the heroes, the Rider villains comprising Great-Valkyrie Empire cooperate with the Armada's Ranger villain members with the intent of taking over the world. Upon learning this, the Riders and the Power Ranger teams all join forces in order to stop their respective enemies once and for all.
The film begins with Captain Marvelous of the High Seas Rangers confronting and defeating the first eight Legendary Riders, which includes Masked Rider, before Kit Taylor appears before him. While Marvelous swears to him he will not rest before all Riders are destroyed, Kit claims he will not stop until all Power Ranger members are vanquished. While watching Earth from the moon, Marcus Armstrong, Olivia Ride, and Mara Shepherd see a series of shooting stars that turn out to be an Armada fleet. Within moments, Astro Academy is invaded by Armada militants as Marcus comes to Damian Collins' aid before being blasted away from the Astro Rider Club to an area where he meets Captain Marvelous. Introducing himself as Ken Glenn and Liv arrive, Marvelous reveals his intent to destroy Marcus as he transforms into High Seas Red. Transforming in response, Astro Rider is overpowered by High Seas Red before sicking the soldiers on him. But, the rest of the High Seas crew and Z.J., as the Red Legend, arrive and take out the Armada soldiers before they attempt to talk Marvelous out of attacking the Riders. Marvelous is unconvinced as he summons his new ship, the Armada Mothership, and calls in Lord Zedd, Prince Vekar, Emperor Mavro, Vrak, Dai-Shi, Sculpin, the Fearcats, and Master Xandred. Though Star Rider arrives to lend a hand, High Sea Red retaliates by summoning the Rider Hunter to cripple Star Rider before inflicting the death blow and tells his crew that Kamen Rider Dragon Knight has already taken the lives of the Mighty Morphin Rangers and some of the other Power Ranger teams.
Meanwhile, the Thunderbirds find people being attacked by various Rider monsters under Doctor X of Shocker. Doctor X then introduces the Rangers to Shocker's Great Leader, Kit Taylor as he transforms into DCD to overpower them. But before he can finish them off, the High Seas Rangers and The Red Legend save them and demand an explanation from Dragon Knight. However, DCD blames Marvelous for starting the fight before a rebuilt Spider Base appears overhead with Doctor X summoning Count Dregon and other numerous monsters to weaken the High Seas Rangers, so DCD destroys Lola, Donny, Allie and Orion as Joe and Z.J. are forced to retreat, but not before Z.J. takes the Silver Morpher and Key left behind.
Elsewhere, Vrak and various Megaforce monsters attack Power Rider as the Double Birth Riders arrive to provide him back up before Rider Hunter arrives. Watching from afar, Marvelous encounters Drew Lansing and reveals his goal to obtain the "Ultimate Treasure in the Universe" by destroying all the Riders. Taking out the two Mach Riders while fighting Kamen Rider Torque, Marvelous is about to destroy his opponent when Trio Rider sacrifices himself to save the other Riders. Taking Nina and the Animal Coins on her person to the Spider Base, Drew confronts Kit after he gave his forces the order to go after the Mega Rangers. Drew explains to a confused Kit that he had regained his memories of being a Kamen Rider by Eubulon in order to help stop the war. Drew and Nina are forced to retreat with Tiger-Roid and Komathunder sent after them as they run into Joe and Z.J. as they debate over their next course. More Great-Valkyrie Empire monsters interrupt their discussion causing Joe and Z.J. to morph into High Seas Blue and Silver (considering Z.J. now has the Silver Morpher and Key at this point in time). At Nina's behest, Drew becomes Torque to wipe out the Great-Valkyrie Empire monsters. Learning that he is a Kamen Rider Joe attempts to take out his frustrations on Drew when Kamen Rider Wing Knight appears as he reveals what Marvelous' intention was while he spares Joe's life upon beating him. From there, Z.J., after calming Joe, says that they all need join forces to solve what is truly going on with Marvelous and Kit.
Seeing that finding one of them is the only way to find answers, Drew takes the others to Dragon Knight as he destroys the Mega Rangers while calling Troy a bad leader in the process. Though they came only to talk, Joe is intent on fighting as another Shocker momster defeats him. However, Marvelous destroys the monster to save Joe and tells his first mate that this is for survival as only one group of heroes can exist. Telling Joe that the Mighty Morphin Red Ranger knows the true story, Marvelous tells him not to interfere as he confronts Kit. With their amassed armies ordered to stand back and watch, Marvelous and Kit transform and do battle. With both High Seas Red and Dragon Knight evenly matched, the fight ends in a stalemate with Joe attacking Drew and Len but lacking the will to destroy them while admitting he does not want to see any more death. When they decide to find the Mighty Morphin Red Ranger, Joe points out that he is dead. Z.J. decides to use the Q-Rex Drill since it has time-traveling capabilities that work with the Time Force Keys. Arriving in 1993 to watch his battle with Goldar, the Red Ranger reveals that he knows why they come and ask them to take him to their time as he is joined by the Jungle Fury Rangers, the Mystic Rangers, the Space Rangers, the S.P.D. B-Squad Rangers, and the Wild Force Rangers. But Masked Rider suddenly arrives with Duo Rider, Accel Rider, and the rest of the Kamen Riders with a battle ensuing where only the Red Ranger and Masked Rider remain.
However, the Red Ranger and Masked Rider are revealed to be Super Megaforce Red and Dragon Knight in disguise as both planned to flush out the remaining opposition and put an end. Mortified with Marvelous's drive to sacrifice their own, a betrayed Joe engages his captain with Len protecting him before being knocked out by Dragon Knight. With both Len and Joe taken out, High Seas Red and Dragon Knight resume their epic battle have been before Doctor X and Rider Hunter arrive and reveal that the Armada and Shocker have been playing them both in order to remove any opposition to combining their fortresses into their own Megazord to take over the world. However, Marvelous and Kit knew of the treachery and played along while sending those they seemingly defeated into the Advent Void until the time to spring their trap arrived. Joined by Marvelous's crew with Orion (Z.J. had already given back the Silver Morpher and Key to Orion beforehand), the Red Legend, Power Rider, and the real Mighty Morphin Red Ranger and Masked Rider as they transform, Dragon Knight and High Seas Red are joined by Astro Rider, Star Rider, the Thunderbird Rangers, and every other Kamen Rider and Power Ranger team to stand against the Shocker-Armada Alliance. However, as the Thunderbird Megazord is formed to fight the enlarged Vekar and Mavro while he and the High Seas Rangers defeats General Shadow, Dragon Knight is horrified to find a revenge-driven Drew as he forms the Valkyrie-Armada Megazord to teach everyone a lesson as the Megazord destroys Mavro and Vekar.
Entering the Megazord, Torque uses it on the Thunderbird Megazord with Astro Rider saving the Yellow Ranger. Given the Rocket Super-1 Switch and a new Astro Switch, Astro Rider takes over the Yellow Ranger's place in piloting the Megazord as it engages the Shocker-Armada Megazord with the Super Rocket-1 Switch giving the Megazord the means to take their opponent into space. Back on Earth, the High Seas Rangers gain Power Rider Ranger Keys to take out Rider Hunter while Doctor X uses the Kani Laser to overpower the Kamen Riders before the Mega Rangers give Dragon Knight, Space Warrior, and DCD their Power Cards to overpower the Destron monster prior to using their signature moves to finish him. However, Doctor X is revealed to be a revived Xaviax as he leaves while telling Dragon Knight that he will never stop until he amd the rest of the Kamen Riders destroyed. Back in space, using Saturn's gravity as a boost, Astro Rider installs the Drill Switch Super-3 on the Thunderbird Megazord to destroy the Shocker-Armada Megazord. Soon after, as Evan and Nina are reunited, the High Seas crew and Z.J. watch Astro Rider befriending the GB Rangers. Marvelous then joins up with his crew and sees the ultimate treasure being friendship between the Riders and the Power Ranger teams while accepting Evan's friendship. As for Drew, having survived the Valkyrie-Armada Megazord's destruction but badly injured, gives Kit back the Torque Advent Deck and tells him to find his own path before accepting Kit's friendship in his own way while leaving.