Diend will receive his final form in Chou Den-O trilogy movie. The concept of design is still same as Decade’s and uses similiar device (look the belt). Diend only has nine eight rider cards in his chest since those riders are only appeared in its movie adaptation. The riders are G4 (Agito), Ryuga (Ryuki), Ouga (Faiz), Glaive (Blade), Kabuki (Hibiki), Caucasus (Kabuto), Arc Kiva (Kiva) and Skull (W). Kuuga has no its own movie and Den-O has too much movie riders even I think they can put New Den-O (Kotaro) on it. For movie which has more than one rider only the strongest who selected. Can’t wait to see his action ^o^ Source.
See also W and Accel Final Form.