I'm sorry, Candescence, I mean you no disrespect but this is exactly the sort of thing I was afraid of. It's the Zybourne Clock all over again. The proposed story and plot is much too convoluted, there is nothing concrete... just vague summaries that are weakly connected at best. The themes as well are rather cliched and the treatment has a decidely fanfiction feel to it.
The idea of a "Brawling RPG Platformer that has aspects of every genre ever" is quite frankly much too ambitious, bordering on ludicrous. It's just not a realistic goal.
The level of detail you're looking for would push this into a couple years of development time. Construct 2 will be out by then, so the idea that this would be a project to show off Construct is pretty much out the window.
Furthermore, this seems less a vehicle to showcase Construct's capabilities and more to show your ideas for stories and characters.
If a realistic group project is going to happen, the themes and stories are going to have to be simple and straightforward. Think more arcade action than RPG action. Sure, it can look good and showcase Construct's features, but it doesn't have to be the Godfather of RPG games. You can show bone animation, shaders, texture distortion, physics, etc. without time-bendingly convoluted plots about teenagers who have dreams of mystical artifacts and whatever else.
Just my two cents, I'm trying to be as real as possible here and again I mean no disrespect. It's going to be a lot easier just making an action game with a simple story (that is, if you even need any story at all).