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After thinking it over I have decided on Water. It is a good threat or at least neutral against most of the OU and the 2 and 1/2 that dont care about water (Zapdo,Pyroak and some build of Stratagem) can potentially be made less threatening down the line.
A watermon, in theory, should be able to check Strategem, Tyranitar, Fidgit, and Heatran. If it's a special attacker maybe Scizor too. If physical, Aqua jet would be incredibly useful for taking out Strategem.