In Viewtiful Joe 2, the plot resolves around Joe and Silvia getting the seven Rainbow Oscars. Captain Blue was turned into the Blue Oscar because he gave the movie a happy ending. Joe and Silvia are sent to the first movie and once they defeat the boss, a new Oscar appears. Joe's father, Jet, berates the two for rummaging through his classic film collection. So the Brilliance is because Jet is the Black Emperor and has the Black Film, he's had his whole life to track down the movies that hold the power of the Rainbow Oscars and needed Joe and Silvia to give the movies a happy ending.
Or is it Fridge Horror that Jet has gone and defeated all the original heroes of these movies and turned them into the other Rainbow Oscars?
Given that the Black Film was manipulating Jet, corrupting his wishes to be the ultimate hero for his son's sake, not to mention the unresolved Sequel Hook that there was a Man Behind the Man, the situation is ambiguous enough that both are simultaneously possible.
Why does the Black Emperor turn white after absorbing the power of the Rainbow Oscars? Because white is the result of every color combined!