The Rider Battle (ライダーバトル Raidā Batoru) was a tournament fought in the World of Decade, the home world of Kamen Rider Decade, Tsukasa Kadoya. It was actually a trick by Dai-Shocker to have the Riders crush each other so they wouldn't interfere with Dai-Shocker's plans. Kamen Rider Decade: All Riders vs. Dai-Shocker