The Clock and the Flame are to "partner" with H&H! 

The Clock debuted in Funny Picture Stories #1, published by Comics Magazine Company, in November 1936, predating Superman by about a year and a half.  The Flame debuted in Wonderworld Comics #3, published by Fox Feature Syndicate, in July 1939.  He was created by Will Eisner and Lou Fine.

What do they have to do with Hideouts & Hoodlums?  By virtue of being public domain characters, they will be able to help fill out the illustrations for the H&H core rulebooks.