Nintendo should just have an adventure that takes place through the whole place, like you start in Johto, go to Hoenn, get to Sinnoh, then fight the 'Champions', in which there is 4 people (and your rival), and each is specifically awsome.
1st: Yuil, Ice trainer: Glaceon, Snowlass, Lapras, Mamoswine, Glaceon.
2nd: Krek, Dragon trainer: Flygon, Dragonite, Salamence, Kingdra, Gyrados (Ode to Red/Blue version).
3rd: Oll, Normal trainer: Slaking, Togekiss, Snorlax, Porygon-Z, Blissey.
4th: Keur, Steel trainer: Lucario, Probopass, Magnezone, Aggron, Metagross.
5th: Gary, All: Gardevoir, Blaziken, Tyranitar, Dusknoir, Garchomp, Suicune (How awsome would it be if someone else had a legendary for once, and when you beat him, Suicune becomes a runner and on rematchs gets replaced with shiny Vaporeon.)
That would be a fun 'Champion' 4.