What they need to do is make Mudkip a catchable Pokemon. Everyone loves Mudkips. In fact, make the next legendary like a giant Mudkip. Gigamudkip or something.

In all seriousness, they don't need to make the legendaries bigger and better. In fact, can they? Arceus is effectively God of all Pokemon. Why not just some Pokemon that are better than others? That's what Mewtwo and the birds were. Have the 3 Legendary...fish or something.

I'm hoping they stop all this nonsense of their being evil teams wishing to control the Earth with uber Pogeys. Why not just go back to Team Rocket who you foil occasionally? Why can't the main basis of the game just be going to catch some Pogeys? If I was trying to be a Mudkip master and I couldn't do a gym because I needed to go find the Special Rock to awaken an uber Pogey, I'd be pissed off.

One thing I'd like to see is jobs or specialisation or something that could enhance your status, for example, Trainers get more XP per battle, Breeders breed better Pokemon faster, Co-ordinators fare better in contests, Collectors are more likely to find rare Pokemon, and specialising in a particular type enhances Pokemon of that type's performance in battle.

If the next generation is Fire/Water/Grass, followed by ten hours of Pidgey/Rattata/Bug/Zubat/Geodude spam, some lame main-story involving an uber, catching that uber, Elite 4, then win. Oh, and you have an annoying rival. Gary was the only cool rival. Oh yeah, if any of that happens, you all die.