3. Intergang
For those wanting to see Darkseid, an interesting way to introduce him gradually might be to introduce the Intergang first. Bruno Mannheim is the apparent leader of Intergang - an organised crime group who are armed with weapons from the planet Apokolips. A movie role for the gang could see them committing crimes all over Metropolis, forcing Superman to step in. Expecting to casually apprehend them, they could then use their weapons to defeat him - at which point it would become apparent that they are not weapons of Earth. Once Superman has beaten them once and for all, the big Darkseid reveal could come in much the same way that Thanos was revealed at the mid-point of the credits in
Avengers: Assemble, showing him as the mastermind behind the gang, having been manipulating Mannheim, and foreshadowing his appearance as the major villain in a future movie. Whether or not the little-known group could carry a film as the only physical threat throughout is open to debate, but it would certainly be an interesting side-plot to be taking place and, as previously mentioned, a novel way to introduce Darkseid in the DC cinematic universe.