The company traditionally gets permission to use characters like Barbie and Ken, Mr. Potato head or Slinky, etc. When they can’t gain permission – for example G.I. Joe said no to licensing rights – the franchise will sometimes invent characters with similarities to popular types or genres of toys but that aren’t the same thing.
Combat Carl, for example, hasn’t been specifically tied to G.I. Joe but has some similarities to that type of toy.
Duke Caboom has some similarities to Knievel’s toys, but Duke Caboom’s characterization is more unfamiliar, as he’s Canadian, emotionally stunted, and scared of the stuntwork he was created to perform.