Movie War

The Movie War Series (MOVIE大戦シリーズ) is a recent group of movies that serve as crossovers with two immediate Series installments within the Kamen Rider franchise, having started with W and Decade, the former being the first show of the Neo-Heisei era. They are shown around mid-December. Every movie so far has featured all the leading Neo-Heisei riders at the time, thus, Kamen Rider Double has appeared in all of them.

It can be considered the Kamen Rider Series' equivalent to the of Super Sentai, which had celebrated its 15th anniversary before the start of the Movie War Series.

Similar to how Kamen Rider Decade: All Riders vs. Dai-Shocker started the tradition of Summer Movies featuring a cameo appearance of the lead Kamen Rider of the up-coming new series, the Movie War films feature a cameo appearance of the Secondary Rider of the current series.

Trends

 * Movie War films normally feature movie exclusive Riders
 * Movie War 2010 - Kamen Rider Kiva-la and Kamen Rider Skull
 * Movie War Core - Kamen Rider Core
 * Movie War Mega Max - Kamen Rider Aqua/Poseidon and Kamen Rider Nadeshiko
 * Movie War Ultimatum, rather than featuring new riders, features new versions of classic Ishinomori heroes (Poitrine, Inazuman and the villainous Akumaizer trio)
 * As mentioned, they open in theaters in December, placing them after the end of the previous series and somewhere between episodes 10 and 20 of the current series.
 * Movie War films have a title format of Kamen Rider × Kamen Rider (current series) & (previous series): Movie War (blank).
 * They usually feature the current and previous Kamen Riders assuming a new form:
 * Movie War 2010 - Final Form Ride Double CycloneCyclone & JokerJoker and Decade Violent Emotion
 * Movie War Core, rather than featuring new movie-exclusive forms for the lead riders, features an incomplete form for Kamen Rider Skull called Skull Crystal
 * Movie War Mega Max - Fourze Rocket States and OOO Super Tatoba Combo
 * Movie War Ultimatum - Wizard Special Rush and Fourze Meteor Nadeshiko Fusion States
 * At some point in these films, the previous rider assumes his Extra Final Form, while the current rider assumes his (near-)Super Form. This is usually during the final battle, where their powers are equal:
 * Movie War 2010 - Decade Violent Emotion (Extra Final Form) and Double FangJoker (Super Form)
 * Movie War Core - Double CycloneJokerGoldXtreme (Extra Final Form) and OOO Tajadol Combo (Super Form)
 * Movie War Mega Max - OOO Super Tatoba Combo (Extra Final Form) and Fourze Rocket States (near-Super Form)
 * Movie War Ultimatum - Fourze Meteor Nadeshiko Fusion States (Extra Final Form) and Wizard Special Rush (near-Super Form)
 * Each Movie War film features the introduction of the current series Secondary Rider:
 * Movie War 2010 - Kamen Rider Accel
 * Movie War Core - Kamen Rider Birth
 * Movie War Mega Max - Kamen Rider Meteor
 * Movie War Ultimatum - Kamen Rider Beast
 * Unlike films in the Super Sentai Movie War films are normally made up of three parts, the first part is an epilogue to the previous series, and the second part is a new adventure in the current series, with the third and final part being shorter in length and featuring the actual crossover between the two shows.
 * Movie War 2010 is made up of Kamen Rider Decade: The Last Story, Kamen Rider W: Begins Night, and Movie War 2010.
 * Movie War Core is made up of Kamen Rider Skull: Message for Double, Kamen Rider OOO: Nobunaga's Desire, and Movie War Core.
 * Movie War Mega Max is a special case, as it is divided into five parts rather than three, to celebrate the 40th anniversary of the Kamen Rider Series. It is made up of Beginning: Fight! Legendary Seven Riders, Kamen Rider OOO: Ankh's Resurrection, the Medals of the Future, and the Leading Hope, Futo, The Conspiracy Advances: Gallant! Kamen Rider Joker, Kamen Rider Fourze: Nade-Shiko Ad-Vent, and Movie War Mega Max.
 * Movie War Ultimatum is made up of the beginning, Kamen Rider Fourze's portion, Kamen Rider Wizard's portion, and Movie War Ultimatum.
 * The Movie War films also features elements of Kamen Riders beyond the two featured series.
 * Movie War 2010 features the conclusion to the Rider War as well as the return of the Nine Worlds' Kamen Riders, as Kamen Rider Decade was a crossover series celebrating the 10th anniversary of the Heisei Kamen Rider Series.
 * Movie War Core has Kamen Rider Core, the main antagonist who is an amalgamation of the memories of all previous Riders and their battles.
 * Movie War Mega Max celebrates the 40th anniversary year of the Kamen Rider Series, featured the Seven Legendary Riders as well as Kamen Rider Double returning to assist OOO and Fourze, uniting the first three protagonist Riders of the Neo-Heisei era.
 * Movie War Ultimatum features all the main Riders and secondary Riders of the Neo-Heisei era as of Kamen Rider Wizard, as Kamen Riders OOO and Birth, with Double and Accel, come to help Wizard, Fourze, Meteor, and Nadeshiko, with Kamen Rider Beast making a cameo.
 * Thanks to the previous trend, all Movie War films have featured the first protagonist Neo-Heisei rider, Kamen Rider Double, originally as one of the main characters later as an older supporting Rider.
 * Unlike the Summer Movies and the  films, Movie War films are not accompanied by a series of Net Movies.