Kamen Riders' Crossover Forms

Crossover Forms are Rider Forms assumed by Kamen Riders that feature elements outside of the Riders' native series. Most of these forms utilize the powers of another Rider, either the protagonist's immediate predecessor or successor. In some other cases, the form is the power of a Rider who is not the immediate predecessor or successor. These forms, like Hyper Battle forms, are usually used only once or twice and are never mentioned or used in series canon again.

The real world purpose of these forms are threefold: to advertise the Legend Rider toy devices that Bandai sells annually, a special addition to the Riders power's for the Movie War films to add to the excitement for moviegoers and the forms acting as playable form change power ups for the Ganbarizing game.

Kamen Rider Decade

 * Decade is able to assume the form of various past Kamen Riders, for a full list see Kamen Rides. Both Decade and Diend's Complete Forms allow them to use the powers of past Riders as well.

Kamen Rider OOO

 * Kamen Rider OOO
 * Tamashii Combo (OOO, Den-O, All Riders: Let's Go Kamen Riders) *erased from existence due to restoration of original timeline.

Kamen Rider Drive

 * Kamen Rider Drive
 * Type Fruits (Kamen Rider × Kamen Rider Drive & Gaim: Movie War Full Throttle)

Kamen Rider Ex-Aid
Ex-Aid=
 * Kamen Rider Ex-Aid
 * Ghost Gamer (Kamen Rider Heisei Generations: Dr. Pac-Man vs. Ex-Aid & Ghost with Legend Rider, Kamen Rider Ex-Aid "Tricks": Kamen Rider Genm "Legend Rider Stage")
 * Level 1
 * Level 2
 * Drive Gamer (Kamen Rider Ex-Aid "Tricks": Kamen Rider Genm "Legend Rider Stage")
 * Level 1
 * Level 2
 * Gaim Gamer (Kamen Rider Ex-Aid "Tricks": Kamen Rider Genm "Legend Rider Stage")
 * Level 1
 * Level 2
 * Ichigou Gamer (Kamen Rider Battle: Ganbarizing)
 * Level 1
 * Level 2
 * Kuuga Gamer (Kamen Rider Battle: Ganbarizing)
 * Level 1
 * Level 2
 * Ryuki Gamer (Kamen Rider Battle: Ganbarizing)
 * Level 1
 * Level 2
 * Kabuto Gamer (Kamen Rider Battle: Ganbarizing)
 * Level 1
 * Level 2
 * Kiva Gamer (Kamen Rider Battle: Ganbarizing)
 * Level 1
 * Level 2
 * Decade Gamer (Kamen Rider Battle: Ganbarizing)
 * Level 1
 * Level 2
 * Double Gamer (Kamen Rider Battle: Ganbarizing)
 * Level 1
 * Level 2