The Plot: Ghost Rider heads to LA, and becomes part of a superhero team-up, although they don't exactly give The Avengers a run for their money. The gang is set up by X-Men's Angel, lead by Black Widow, and also features Ice-Man, Black Goliath and Darkstar, though tensions within the group meant that Angel was eventually forced to disband the team. The Villain: Titanium Man (think evil version of Iron Man). Cast an unknown as it'll be the hulking great suit that makes an impact.
Likelihood? The Champions would probably be best reserved in case Marvel need to go bigger for an Avengers sequel.