Sounds vaguely like a Mario & Luigi RPG game of some sort. They often play around with Mario and Luigi doing different things or swapping between modes.
Have you played The World Ends With You? In that game, using the Nintendo DS's dual-screens, each character is fighting on a different screen.
It sounds like the mechanic could work - but execution is everything.
Swapping stats sounds like it removes each prince's individuality - I, as a player, no longer need to care about the differences between them. In my mind they then become one character in two bodies, rather than two unique characters. This may be what you are going for, plot-wise*, but makes the game less interesting, character-wise.
*Cliched plot twist: they aren't really twins, they are same person who got split apart in two or more bodies.
I've played RPG games and majority of them are pretty much the same.
By "the same", do you mean they have ceased to be enjoyable to you, or that they weren't really enjoyable to you in the first place?
Why have they ceased to be enjoyable? Have your tastes in genre changed, or have you just played similar RPGs so much that you feel like you're just replaying the same game over and over?
What parts have ceased to be enjoyable? How would you go about improving - or removing - those parts?
How can you take the RPG genre and distill it, refine it, build upon it, polish it, and improve it?
So I want to do something new to the genre.
Are you doing something different just for the sake of being different, or are you trying to do something better and make things more enjoyable?
Different doesn't always mean better. Different doesn't always mean enjoyable. Sometimes they can be improvements, other times they are just gimmicks that are entertaining for one game, but aren't really lasting improvements to the genre. Which is fine - the occasional gimmick-game can be enjoyable. Are you designing a gimmick game?
I was inspired to do this mechanic after playing Bowser's inside story. The thing is though that the Mario rpgs don't require a lot of grinding process in order to make progress. The idea of this mechanic is that I want anyone to enjoy RPG's not because of its gameplay but also because of the genre having well written stories and people who play it halfway won't get to enjoy the rest of the story. So yes, you can say that I'm making a gimmicky game.
Some of you mentioned that the game wouldn't work with swapping stats and I want to tell you that levelling up in this game is not so frequent as it would in any RPG. you can battle tougher bosses with low levels, something that cannot be done in rpgs. Therefore the game will be really fun to those who aren't interested in RPG's normally
When playing RPG's, there are various things in common. grinding, talking to characters to find out what to do, facing bosses, watching cutscenes and then facing climaxes. While its understandable why everyone likes this process in RPG's, it will leave others not that interested because of one factor that can potentially stop players from playing. Grinding and I want to make that process more enjoyable by improving in it.
Another problem RPG's have is once the game is beaten, there really is no point in revisiting the game unless the game offers story branching such as Chrono Trigger. Then Side quests only give the benefit of the player getting more powerful rather than offering something else like unlocking concept art and such.
The world ends with you is an action rpg whereas I'm making an RPG game instead. As for the character wise, its not going to be as cliche as you think it would in my defense atleast. I'm going to bring out branching paths for the story like trigger.