Before you even begin to read this potential set, be aware that it intends to run Whimsicott offensively. I'll wait until you finish facepalming...Done? Ok then, let's get started.
Whimsicott@Life Orb
Nature: Modest
Ability: Prankster
EVs: 252 SpA, 252 Spe, 4 Hp
-Cotton Guard/Light Screen
-Light Screen/Cottonguard/HP Fire
-Solar Beam
-HP Fire/Fake Tears
I was attempting to create some set that is completely crazy, but just crazy enough to work, seeing how nobody expects a freaking offensive Whimsicott. I noticed that, while having stats that make an offensive variant laughable, it has a few awesome moves that, thanks to Prankster, can allow it to (hopefully) survive and claim at least one kill for several turns. It also has access to a Life-orbed STAB Solar Beam, which on a sun team requires no charge and can devastate the opponent.
For the first move, Cotton Guard is preferable, seeing as how it makes Whimsicott's Def skyrocket up to 525,
at a minimum. Light Screen can be life-saving, as it causes Whimsicott's SpD to reach 310 at a minimum, which can be enough to take stray ice beams from bulky waters. The second move is much of the same. However, if one defense-boosting move is not necessary for your needs, then HP Fire could take it's place. Solar Beam is the crux of the set, as it is Whimsicott's most powerful attacking move. The last move mainly depends on your previous move choice. If HP fire was used, Fake Tears can half the opponent's special defense, which makes all but the most specially defensive opponents OHKO'd (yes, I'm looking at you Blissey and Jellicent). If cg and ls are being used, then HP Fire can be used to destroy any steels/grass pokemon (i.e. Jurachi, Celebi, Ferrothorn, Skarmory, Scizor, Forrettress...SO MANY STEELS WOULD NOT EXPECT THIS).
Damage Calcs : COMING SOON...(if anybody runs any, please post results)
Threats: TO BE CONTINUED...somewhat
-Changes in weather pretty much screw it over. Solar Beam takes two turns to charge unless the sun comes back out, and HP Fire drops to 60 base power. If you were to use solarbeam, and your opponent switches to T-tar, Hippowdon, or Politoad (the most common Pokemon that change weather), unless he/she switches that turn, Solarbeam is going to hit hard. This prompts the switch into something which can likely take the solarbeam.
-Heatran. Nothing needs to be said here. It's Heatran vs. grass,fire, and bug moves.
This set has the potential to work due to Whimsicott's base 117 speed, +1 priority to non-attacking moves, and the ability to boost for defense. Perhaps the greatest chance of this set succeeding lies in it's surprise factor...