Mainstay is Clefable, followed by other Metronome Pokemon for Flavor.
Get a Clefable online as Step 1, then for the low-low cost of 1 Recycle Energy, Gust of Wind out whatever your opponent's strongest Pokemon is, add a Plus Power, attach a Focus Band for survivability, and Metronome a more damaging version of it's strongest attack for serious value.
Energy Removal to strip your opponent of the opportunity to attack you back to ensure the Clefable can survive longer as well.