I think it would be pretty cool if they had a Pokémon game that tied all of the regions together. If they did they would have to either make it to where you send all of your Pokémon back to the lab or make it to where there basically has no level cap. Or it would be cool if they make an online Pokémon game to where you can walk around and interact with anyone that's playing. Or if they put the two ideas together would be even better. But if they did that they would have to go all out and make it in a 3d world and put it on the wii or the wii U(I prefer wii U cause of the tablet controller so many possibilities with that.

I have actually been thinking a lot about this lately. Kanto and Johto are connected in Generation's 2 and 4; Hoenn and Kanto's Sevii islands are close by ( take Faraway island for example), and in Gen 4 there is mention of a trade route between Sinnoh and Johto.

What if, instead of doing one game with all the areas, Nintendo made separate versions with different areas? For example, in one version you would start in Hoenn, go to Johto, than finish in Kanto. In the other, You could start in Sinnoh and go to Kanto then Johto. A third version, keeping with tradition, could be released a few years later and include a way to connect Unova.

About keeping Pokémon at the lab: what if, instead, they were returned to you slowly? After earning Misty's badge in red/blue, you could control traded Pokémon under level 30. In these games, though all your previously captured Pokémon under level 30 could be returned to you after you beat that gym.

I think they have something kinda like that in Ash Grey but I don't think it goes to different regions I wish though.

I think it would be cool if they did make a game tying all the regions and pokemon together for DS or 3DS or even PC.. It would be really cool to catch all the Pokemon and beat all the gym leaders across all regions in one game.