Whimsicott

With access to Prankster and a huge supporting movepool, Whimsicott is very useful for disrupting the opposing team. Its base 116 Speed makes Whimsicott the fastest Prankster user in the Battle Spot metagame, outspeeding other Prankster users such as Thundurus, Liepard, Klefki, and Sableye along with base 115 Speed Pokemon such as Raikou and Starmie. Whimsicott's Fairy / Grass typing is great defensively, giving it an immunity to Dragon and some useful resistances, such as to Fighting, Dark, Water, Electric, and Ground, but it also gives Whimsicott an extra weakness to Steel and a 4x weakness to Poison. Whimsicott is also an excellent stallbreaker, being able to utilize Encore + Taunt against defensive Pokemon, such as Chansey, Clefable, and Cresselia, locking them into a status move and causing them to use Struggle afterwards.

However, Whimsicott has little to no offensive presence, leaving it with very few attacking options outside of its STAB attacks Moonblast and Giga Drain. Its 60 / 85 / 75 bulk leaves a lot to be desired, which prevents Whimsicott from being able to take several strong attacks. Because of Whimsicott's reliance on support moves, it often becomes bait for other Taunt users if it isn't running Taunt itself. Whimsicott also lacks reliable recovery outside of Leech Seed, so it's heavily reliant upon the move. Its typing also gives it trouble against Fire-, Flying-, Steel-, Poison-, and Ice-types such as Talonflame, Heatran, Gengar, and Mamoswine.