Some might not regard this as a true crossover, since the characters are now all owned by one company. However, in the 1940s, three different publishers actually produced the adventures of the various members. The original superhero team, their first issue indicates how differently each character was treated. The gang get together to swap adventure stories, and each story, written and illustrated by different talents, maintains the house style and mileau of each respective character. Even the comical Red Tornado makes a brief appearance:

The JSA also set the record, still unbroken, for poor fashion sense as a metahuman Achilles' Heel. Seriously, the Flash would be using his super-speed to run back and pick up that Hermes hat, and Dr. Fate would need his mystic powers just to see out of his helmet. The Green Lantern (second from the right) apparently suffers from colour-blindness. Presumably, so does the Sandman, or he wouldn't be wearing an orange hat, yellow mask, green suit, red gloves, and purple cape (although I prefer this uniform's originality to the rather generic tights he later wears).

Another beguiling decision was made by Hourman, who has impressive super-powers, but only for one hour at a time. That's a great weakness to use when plotting his adventures (though writers frequently forgot about it), but really, do you want your vulnerability advertised every time someone says your name?