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.