SmogonWP

SmogonWP is a Windows Phone client for Smogon (http://smogon.com). It also has some non-Smogon stuff that's still relevant to the world of Pokemon.

The app is currently on the Windows Phone store! You can download it here. If that link doesn't work you, try searching for SmogonWP in the store app itself, the app should be available in all regions for all WP8 devices.