When you think superheroes you think super-teams, which help to define the individual members in the context of their fellow teammates. While there are more prominent teams in the cosmos, for our purposes here today we center on two with significant parallels.
The Squadron of Justice from Earth-S was recruited by Shazam when he and his Marvel Family were left powerless by ancient adversary King Kull. Formed out of sheer necessity, some of these previously joined forces in another team during the 1940's known as the Crime Crusaders Club. Surviving into the modern day thanks to the bumbling machinations of Doctor Sivana, these still youthful heroes joined forces to stem the tide of Kull's villainous hordes on three Earths including their own Earth-S. And then they faded back into retirement aside from scant appearances thereafter.
Remarkably, there was an earlier Squadron of Justice that consisted of Captain Marvel and his three Lieutenant Marvels of Fat Marvel, Hill Marvel and Tall Marvel that operated during the 1940's.
And the progenitor of the modern incarnation of the Squadron was Captain Marvel Junior's known as the Crime Crusaders Club. However, that Club was more of a meeting of Junior, Minute Man, Bulletman and Bulletgirl solely for the purpose of recounting their latest cases and occasionally team up to handle social issues rather than criminal threats. Thus, the Crusaders filled the role that the Seven Soldiers of Victory had on Earth-Two. The vast majority of teamup tales on Earth-S were of the Marvel Family, that world's version of the Justice Society satellite team Super Squad of the Justice League unofficial affiliate of the Super Friends... both of which like the Crusaders operated out of their respective worlds' Gotham City.
The Sentinels of Justice on Earth-Four formed also on one occasion, although there was a hint during their first appearance that they previously met up, and battled a crime lords super-armored forces to save criticial solar technology. The next appearance of this team was during the Crisis on Infinite Earths, when their initial membership of four expanded to included three more drawn towards the presence of heroes arriving from two other Earths, the same two from whom the Squadron met earlier!
The Squadron's membership constituted Ibac, Spy Smasher, Bulletman and Bulletgirl, Mister Scarlet and Pinky, as well as allies Captain Marvel, Mary Marvel and Captain Marvel Junior (and, of course, the team's founder Mercury who brought them all together under Shazam's suggestion). The Sentinels membership originally comprised Captain Atom, Nightshade, Blue Beetle and the Question with later allies Peacemaker, Thunderbolt and a time lost Judomaster joining forces with them.
Alas, the history of each was fleeting at best. But the potential for both was sky high!
In 1954, aspiring comic book publisher Charlton purchased the rights to several prominent characters from the expiring Fawcett Comics, such as Ibis, Golden Arrow and Lance O'Casey. In 1980 and 1985, DC Comics purchase Fawcett's Marvel Family then Charlton's Action Heroes, and the two were linked once more, now on parallel Earths, Four and Shazam.