Really I think all they need is 365 Pokemon. That is one for every day of the year. That way you can pick your Birthday and have a Birthday Pokemon :) I think they should get rid of a bunch of Pokemon (Lotad family, Seviper, Dustox many others.) I think a few additions would be good (The Dogfish looks dumb) I would like more customization in the game. I want to be able to pick any Basic Pokemon I want for my starting Pokemon (I'd want Shellder). I think we should be able to pick out clothing, equiptment, starting town and class (Breeder, Trainer, Coordinator). I think there should be Day/Night, Seasons and Weather. I would like Pokeballs to be more specific. Pokeball, Master Ball, Lure Ball, Park Ball, Safari Ball, Net Ball, we don't need all those other in-between Balls.
I think the best thing they could do would be to make it a worldwide thing. I want World-wide dueling. I want to be able to hook up to the internet and duel my friend in Canada while im eating popcorn in Utah...
BUT!!! If they do anything they BETTER put Shellder in the next game! (Anyone notice Shellder always has his tongue sticking out yet he doesn't/can't learn Lick)