Weather Slayer
although I like the Idea of Momentum in games, I believe that a pokemon purely to defeat the users of weather will able to be implemented not only more often, but with less chance of being classed as "overpowered" - a pokemon based upon regaining momentum will be able to defeat almost any team, not just a select few.
Weather is being used too much, and as a result, a Pokemon dedicated to defeating the weather will lower the weather's use, and bring more balance to all kinds of teams...