Another idea that I find plausible and, considering our technology these days, quite needed, is voicing the Pokémon with real voice acting, like in the anime. It's gonna be disappointing if they keep just making those strange sounds.
Heck, it's a portable console with cartridges that hold up to 4 GB of data, or so I've heard. It is completely possible to make actual voicing for a game like Pokémon, and come on, it'd be EXTREMELY EPIC!
I hope Nintendo knows that and really make the franchise evolve, as they claimed they'd do.