Zu-Zain-Da

Zu-Zain-Da (ズ･ザイン･ダ)/Unidentified Life Form #22 (未確認生命体二十二号)/B3 (Ｂ群３号): The leader of the Zu, Zain is able to assume the form of a hulking strongman with a temper. Soon after the Me group's turn begins with the Zu no longer worthy to play, and when their first hideout got compromised by the police's smoke bombs, Zain starts acting on his own by attacking trucks and jabbing the drivers to death with his horn. He overpowered Kuuga in both human and Gurongi forms when Biran intervened as Zain stole his turn. While Zain resumes his attack on large motor vehicles, Yuusuke manages to perfect his Mighty Kick to finally kill the Gurongi.

OOO, Den-O, All Riders: Let's Go Kamen Riders
To be added