Oy. Enough replies for me to actually give input. So here I go! (P.S.: Thanks for not shutting it down! I feared that could happen!)
Okay, so we have the Elite 4, the most powerful trainers below the Champion. Note the number. 4. Which means that only four trainers can be in the group. Now, this may sound like nothing, but... well, let's see. In all games, upon reaching the 'enemy citadel'/final area with people, you battle 5 trainers, right? Well, four of these are the Elites and the fifth is the Champion. It's a mutually excludent role.
However, it seems that most people believe in the existance of an Elite 5, which equals the 4 Elites and the Champion in the same group. (Maybe came from the original guides to the Japanese versions of Pokémon GS... I remember one that distinctly called them the Elite 5 instead of the Elite 4.)
The problem is obvious, however; the Elites are always entitled as such, and it's always 4. Not 5, 4. The Champion gets a separate title.
So, basically, what I'm trying to say is that the Champion cannot be considered a member of the Elite 4. Because he's supposed to be of a different rank!
So, my point is that anyone who writes Green/Gary, Lance (when talking of the Johto people), Steven, and Wallace as the leaders of the Elite 4 is inherently wrong. Do they have a powerful role in the Pokémon... 'association' (is there a term for the association that takes care of everything?)? Sure. Are they the most important trainers in the world? Definitely. Are they the leaders? Why do people keep thinking that?
So, to sum everything... Lance is the leader in RBY/FRLG fics, Karen is the leader in GSC fics, and Drake is the leader of the RSE fics.
Next question... how important do/would you write the Elite 4, in your world?