I completely agree. Colosseum and Gale of Darkness, from what I could tell, tried to add in RPG elements, but they weren't very good.
Now, don't get me wrong, I really like the Stadium games and Battle Revolution looks amazing, but I'd love a massive, Wii Pokemon RPG with huge cities, vast wilderness, crazy gyms, and massive stadiums for League battles.
Actually,that reminds me of a mock poster of a Pokemon MMORPG I saw awhile back. I could totally see that, with each character being a trainer and you have League standing and such, with a massive League battle every couple of months.