Since a Justice League movie is once again being tossed around, I think the leads need to be introduced to the general populace. Batman, Superman, Wonder Woman, and Flash don't really need intros, but Martian Manhunter and Aquaman could use a stand-up launching pad. And it could be done as long as the effects don't suck and the stories just make sense without too many holes. Play up the drama in both of their lives. The death of MM's entire species, and him witnessing the death of his family, has driven him through out his life on earth. And Aquaman's loss of his son to his greatest foe makes for great soap opera stuff. Throw in an alien wife and a kingdom that has rejected his leadership, you have a man who struggles to regain his identity.
Though, both suck with the weaknesses. A lit cigarette takes down MM, and Aquaman needs to be moist at least once a day.