It's kind of funny how Malaconda ended up becoming a great addition to rain teams despite all the effort to prevent exactly that. In fact, I think Malaconda is more useful to rain teams than sun teams since they have trouble against Heatran and Malaconda only compounds that weakness. Ironically non-specs Heatran is walled by Malaconda in the rain, which is extremely useful if you carry pokemon such as Scizor in your rain team. Malaconda is definitely going to increase the usage of anything that learns U-Turn, its main weakness. But lower the usage of rain teams? Not by a long shot.