Perhaps first on everyone's list of the second tier characters from Detective Comics after the Batman Family (excluding long-underwear types like Crimson Avenger, Air Wave, etc) would be these two who appeared right from the start.
"Slam" Bradley and “Shorty” Morgan were early standard-barer of that title, and predecessors of Batman. Not as colorfully garbed nor equipped with gadgetry like the masked mystery men who came later, they were nevertheless just as resourceful with their wits and wisdom.
Slam was witty and gruff, Shorty was comical and earnest. While Bradley was a private detective attached to Cleveland's police department however loosely, Shorty joined Slam in his crime-fighting crusade, with the pair becoming the original Dynamic Duo. Nevertheless, each adopted other identities and/or disguises to get up close and personal with the criminal element they battled.
Slam and Shorty had near identical counterparts, with a pair of these men existing on Earths One and Two. Proof that the Earth-One Bradley existed was when he appears alongside other detectives who were distinctive to that world, such as Roy Raymond, Human Target. The Earth-Two Bradley was seen alongside Silver Ghost and Federal Man Steve Carson.
Decades after his first appearance, Bradley of Earth-One worked alongside fellow detectives of the same publication. spellings, while his Earth-Two counterpart was never seen again, apparently having retired.
Along those whom Bradley encountered on his ocean vessel was the illusionist Richard “Mysto” Carter and his mammoth assistant Sihki. The pair’s counterparts Doc “Hocus” and Flannelhead “Pocus” were also illusionists, only instead of using slight of hand skills like Mysto, Hocus relied on the secret assistance of the Earth-Two Superman.
While Mysto and Sihki traveled around the world uncovering various mysterious criminal schemes using their power of illusion, Hocus and Pocus usually stumbled upon criminal activity which their friends Superman and Lois Lane assisted them in exposing.
