Arriving late for school, as the car was at Pegasus Garage, Kenta learns that that day is graduation picture day. Seeing a beam of light nearby, Kouichiro gets the others out of class to investigate. The five find a seashell before they are attacked by Space Biker Helmedor who wants the shell to fulfill his dreams, overpowering the Megarangers before MegaSilver arrives and engages the biker in a motorcyclists' duel. Suddenly enlarging with his bike, Helmedor battles Super Galaxy Mega before he is forced to shrink and retreat. Later, while trying to find out the seashell's true nature, Miku uses it to wish for a big cake before it is stolen by a group of strange students who actually are the staff of the Pegasus Garage. But with Mega Yellow placing a tracer on the getaway car, the Megarangers track them to the Pegasus Garage where Kyosuke wishes for Katsudon before he and his team are attacked by Yugande and Kani Nezilar. Refusing to stand aside, they assume their Carranger forms to fight Kani Nezilar while the Megarangers deal with Yugande and the Kunekune. The two Sentai teams join forces to force the Nezireians back as the shell opens up to reveal an alien identified as Space Fairy Picot who wants to grant their last three wishes. Arriving to Yume Beach, the teams get to know each other while talking out to want they would use the last three wishes before Dappu arrives. But "Dappu" turns out to be Helmedor, having made a deal with the Nezirians to get Picot.
As Helmedor runs off, Shibonlena has the Kunekune hold the Megarangers as she uses her power to turn the Carrangers into her slaves and sicks them on the Megarangers. During the fight, the Megarangers find the real Dappu and untie him. In a risky gambit, Dappuin fuses the Megrangers's weapons with his CarMagic to free the Carrangers from Shibolena's spell. At that time, after wishing for a planet destroying laser cannon, Helmedor betrays Kani Nezilar and fights him as Megarangers. After making a wish to revive previous Psycho Nezilars to overpower the Megarangers, Kani Nezilar was about to make the final wish when Helmondo steals the fairy. But the Carrangers get Picot and throw a decoy into the distance to hold the villains at bay. Coming to the students' aid, the Carrangers give them Picot to make the final wish to their shock. By the time Kani Nezilar and a brainwashed Helmondo return to the battlefield, the Megarangers' wish to keep fighting enables them to don the Mega Tector armor. After destroying the revived monsters with Rainbow Impulse, Shibolena has Bedibedi bite Kani Nezilar and Helmedor as Mega Voyager and RV Robo are formed to fight them. Though Helmondo attempts to turn with the planting destroying laser, Mega Winger destroys the weapon as Wing Mega Voyager and RV Robo execute their signature moves to respectively destroy Kani Nezilar and Helmedor. Soon after, Picot leaves for the next planet as the two sentai teams go out to take their own graduation memorial picture at Yume Beach.
Continuity and Placement
Megaranger: The earliest this film can occur is after episode 39 due to Lizard Nezilar being one of the Psycho-Nezilar revived by Crab Nezilar's wish to Picoto. However, episode 39 also is during the arc where the Megaranger are fighting the Neziranger, who are obsessively pursuing the team non-stop; while it could still happen, it would have to take the evil Rangers into account on whether or not they are around. The latest it can occur is before episode 42; likewise due to the Neziranger but in this case due to the storyline that will likewise bring an end both to them and to the dimension of Neziregia where Dr. Hinelar is based.
Though no other Carranger allies other than Dapp appear, they are referenced: the photos at Pegasus Garage show many of their allies, including Signalman and sisters Radietta and Vanity Mirror Fanbelt; while a box-lunch from President Gynamo's shop (which he opens on Earth after the end of the Bowzock) are eaten by the Carranger and Megaranger at one point.
Megaranger vs. Carranger was the third of fourteen crossover movies shown during the Super Sentai Versus Series Theater, a special event on TV Asahi during the run of Tensou Sentai Goseiger. As with the others, this movie was aired in two half-hour parts an hour before the week's episode of Goseiger, there was also commentary at the beginning and end by the Goseigers about the teams and the storylines within the movie.
The end credits recreates the end credits for Megaranger to include the Carrangers and Dapp.