No wonder Doflamingo was confident he could overthrow the entire WG including Imu and the Gorosei, while being afraid of Kaido's name. Kaido's name alone is more haunting than Imu and the Gorosei in person. Heck, even now that Doffy is in jail, they fail to assassinate him. No wonder the WG was afraid to make Kaido angry, as well as admitting they couldn't stop an angry Shanks.