Who says Pokemon never changes? Until recently, the franchise's story wasn't much more than an afterthought. Its main virtue was its consistency – you could always count on an evil organization showing up to destroy the world for no real reason at all. With Pokemon Black and White, a sliver of change was added to adjust the formula and pointed the series toward the possibility of more deft storytelling.
If they wanted to keep the same relative visual style, they could do a celshaded look, like Okami or Wind Waker.
In this world, it's adapt or die, and it doesn't take a rocket scientist to realize how much potential there would be for a (at the very least) partial re-imagining of the series in a larger context.