^ Good question. Hrm. Well, I guess a one-time deal with the roll call could work. Just the elements, not Captain Planet saying his line. If they were to say "Earth" or "Wind" with a whisper, it could work. Makes it more of a concentration to make the ring work rather than a simplistic verbal command. And when Captain Planet shows up after forming, especially the first time, he should be quiet and show nothing but baddassedness with the problem at hand. Then his amalgamation seperates to go back into the Planeteer's rings without saying a word. That's when they speak with Gaia once more. And this is where she explains things--mostly--hinting at her love, and the sacrifice he made, explaining why he was contained into the rings.
It'll be explained that it was for the benefit of man to do what they will with the elements. But it quickly turned to greed and so the rings were hidden. Like a djinn type of story to Captain Planet (Earth). Most people don't know that the original lore of the djinn didn't involve lamps so much as rings. Solomon captured them in rings--supposedly more than one, anyway. Then, all you need do is rub the ring and the djinn will do your bidding. So Arabic mythology could play into a bit.