You could well have Pikachu following Ash around Pallet Town soon enough with the actively developed project Wario's Jewels 7 (WJ7), the first Windows Phone 7 Gameboy emulator. XDA Developers Forum member Badcam3 is collaborating with other developers including Samuel Blanchard to turn this idea into reality.
We know Microsoft doesn't play ball with emulators in the Marketplace (for a good number of reasons), but this is the first sign of light for the homebrew community. To find out more information, check the link below or follow the team on Twitter. The video below shows how you can create your game lists.