Golduck

Golduck is a threatening rain sweeper in PU, outspeeding even Choice Scarf Raichu in the rain by virtue of Swift Swim. Golduck's Life Orb-boosted Hydro Pump in the rain easily OHKOes most offensive Pokemon and 2HKOes almost any special wall that doesn't resist it. It also has useful coverage moves in Psyshock and Ice Beam, allowing it to beat common Pokemon that can take its STAB attack, such as Roselia and Tangela. Golduck also functions well as a threat on non-rain teams by setting up Rain Dance on a forced switch or on a foe that can't deal much damage to it, such as Torkoal. However, Golduck is somewhat slow outside of rain, making it easy to pressure so that it has difficulties setting up rain itself. Additionally, it is easily worn down by Life Orb recoil, and rain turns can be stalled out.