I would actually like this idea: you would have 12 Gym Leaders and have the E4 specialize in Water, Fire, Grass, and Electric. You would fight the E4 and Champion (who uses Normal types) once after the first 4 badges (Bug, Fairy, Poison, and Flying, in any order), ie. the Bronze League, which is up to Lv. 40. The pokes used would be mostly those in their second evolution or some final or not evolved at all. You fight the Silver League after the second set of badges (Ghost, Dark, Fighting and Psychic) which have pokes up to Lv. 70 and are all fully evolved. After the final set of badges (Rock, Ground, Ice, and Steel) you fight the Gold League which has pokes up to Lv. 100 with competitive items like Choice items. So you basically have 3 Pokemon Leagues (which are like rematches). The Super villain team can be Team Draco who specialize in Dragon types. The Police force in the game who aim to take out Team Draco use Normal types. The Champion is also the former Head of the Police force, who quit his/her position to pursue her dreams of competitive Pokemon battling.
This way all 18 types are represented.
Rock type gyms are OVERUSED! I don't want to see a single one in the new game.
There weren't any Rock type Gym Leaders or E4 members in 5th Gen if I recall correctly. So it was a nice break.
I want weather experts e4.. That would be challenging.
If not my idea above then definitely yours. Hail team, Sandstorm Team, Sunny Team, Rain Team, perhaps even a Trick Room Team for the Psychic gym!
I'd want them to change it up a bit, if even slightly. Like having 10 gyms as mentioned above, or having 10 but only having to beat 8 or something.
That's an interesting idea ... having the choice of which gyms to face. How do you think that should be implemented?
Also they should also scale the Gym Leader levels. I'll explain. Since Lumiose city is in the center of the map, what if they gave you a choice in which order to fight the gyms, seeing as all the cities span out of a central one. Then they would change the levels of the Leader's Pokes, their evolution states and items depending on which order you fight them.
Ex) If you fight the Bug Leader first she'll have a Caterpie Level 12. If you fight her 3rd, she'll have a Butterfree Lv. 22 with an Oran Berry. If you fight her 8th, she'll have a Butterfree Lv. 58 with a Choice Specs.
I'm probably not the first to deliver this idea. I know GameXplain said this already.