I felt like throwing my two cents in the ring here as well. If we didn't already have Drowzee as the second control type I would have chosen Watchog as a reference to a certain mind control themed pair of doujin about the Unova girls. An all time favorite of mine. But with Deoxys the third, Watchog would be a massive step down in relative power and break the feeling of progression. Not a complaint at all, just something stuck in my head.