Whimsicott is a potent Tailwind setter in the Regulation G metagame thanks to Prankster in conjunction with its good supporting movepool, and its typing lets it take on staples such as Raging Bolt and both Urshifu formes. Moonblast lets Whimsicott consistently damage bulky Pokemon such as the aforementioned Raging Bolt while also chipping down Rillaboom and Incineroar. It also lets Whimsicott take full advantage of its good matchup against both Urshifu formes, threatening Urshifu-R with a 2HKO and Urshifu-S with an OHKO once its Focus Sash is broken. Whimsicott's ability to punish passive play like Protect via Encore allows fast-paced teammates like Choice Specs Miraidon and Choice Scarf Chi-Yu to safely output huge damage. Encore also has other immensely useful applications like forcing non-Dark-type Fake Out users like Rillaboom and Iron Hands to switch out if they choose to use the move and reversing Trick Room in the face of threats such as Calyrex-I; this is crucial, as Tailwind teams inherently struggle against Trick Room, especially when they have multiple Pokemon weak to the aforementioned Calyrex-I. Light Screen helps bolster Whimsicott and its allies' bulk against threats such as Calyrex-S and Choice Specs Terapagos. Covert Cloak lets Whimsicott safely ignore Fake Out and set up Tailwind, allowing it to threaten with Encore on the following turn. The physical bulk investment allows Whimsicott to avoid an OHKO from -1 Zamazenta-C's Heavy Slam while never being 2HKOed by +1 Body Press. The special bulk investment enables Whimsicott to never be OHKOed by Choice Specs Tera Stellar Terapagos-S's Tera Starstorm and Mystic Water Kyogre's Water Spout in rain even at full power. Maximum Speed is run in order to let Whimsicott have the best chance to force opposing Whimsicott to repeatedly use Tailwind with Encore, which is an interaction that can also be put to use against the slower Tornadus. Tera Fire rids Whimsicott of its weakness to Chien-Pao's Icicle Crash and Incineroar's Flare Blitz among other powerful moves like Calyrex-I's Glacial Lance and Koraidon's sun-boosted Flare Blitz, crucially never getting 2HKOed by Glacial Lance. Alternatively, Tera Water lets it retain its initial resistance to Kyogre's Water Spout and Origin Pulse in addition to the resistances provided by Tera Fire in exchange for sacrificing the positive defensive matchup against Rillaboom and Raging Bolt. Tera Water also provides Whimsicott with a better matchup against Calyrex-I and Pelipper.

Whimsicott, being rather frail, is vulnerable to many relevant Pokemon, most notably Tornadus, as not only does it compete with Whimsicott as a Prankster Tailwind user on nearly every team apart from Miraidon hyper offense, but it also threatens an OHKO with Bleakwind Storm because Whimsicott lacks a Focus Sash. Thus, Miraidon makes for a good partner, as it can easily OHKO Tornadus. Whimsicott supports Choice Specs Miraidon exceptionally well, letting it dish out massive amounts of damage with Tera Electric uncontested under Tailwind. Encore punishes opposing Fake Out users, allowing Choice Specs Miraidon to stay on the field more safely. Whimsicott also helps Chi-Yu do great amounts of damage onto foes thanks to Tailwind and checks Raging Bolt for both it and Miraidon thanks to Beads of Ruin; this is of great value, as Miraidon is otherwise forced to lock into Draco Meteor. Whimsicott is susceptible to being removed by faster Pokemon like Calyrex-I under Trick Room and Chien-Pao, so you should be wise with managing its health and speed control. Iron Hands allows this to happen quite well, not only taking advantage of Trick Room with its low Speed but also heavily threatening Chien-Pao. Its good bulk, access to Fake Out, and healing from Drain Punch allow it to keep Whimsicott safe for multiple turns.

Whimsicott is an excellent Tailwind setter with a deep support movepool, mainly setting itself apart from Tornadus with its higher Speed, access to Encore and Helping Hand, and useful typing that gives it defensive utility against staples like Miraidon, Kyogre, Rillaboom, Raging Bolt, and both Urshifu formes. Moonblast provides a reliable STAB move that lets Whimsicott deal solid damage to common Fairy-weak Pokemon like Miraidon, Koraidon, Chien-Pao, and the Urshifu formes. Encore is Whimsicott's most infamous support option, letting it punish setup sweepers like Calm Mind Terapagos, IronPress Zamazenta-C, and Nasty Plot Calyrex-S for attempting to boost in front of it; the move also punishes foes from trying to stall out Tailwind turns with Protect, and it discourages Rillaboom from using Fake Out lest it be locked into it. Additionally, it forces Trick Room setters like Calyrex-I to untwist the dimensions. Taunt is a similarly useful disruption tool that can be used with or in place of Encore, notably allowing Whimsicott to deny Tailwind from other setters like Tornadus and Lunala unless they use Tera Dark. Protect helps Whimsicott keep itself on the field and stay in a position to use its other moves repeatedly, especially in the face of Fake Out users, but the last moveslot can also be spent on more aggressive options like Helping Hand, which is useful with any attacker, or Fake Tears, which is especially devastating alongside strong special threats like Chi-Yu. Whimsicott enjoys holding a Focus Sash to make up for its poor bulk, and Tera Ghost is useful to prevent the item from being wasted by Fake Out.

Whimsicott's reliable Tailwind support is a blessing to almost every Restricted Pokemon, especially those with middling Speed tiers such as Groudon and Terapagos, as well as Pokemon that want to be faster against opposing Tailwind teams such as Miraidon and Calyrex-S. All four of those Pokemon also benefit from Encore, which can create space for them to set up with Swords Dance, Nasty Plot, and Calm Mind. Clear Amulet Koraidon is another notable partner that reliably discourages opponents from bringing Incineroar, which is easily the worst Pokemon for Whimsicott to face in a battle. Other strong attackers that benefit from Tailwind support are also great with it; Landorus and Urshifu-S both fall into this category, and Chi-Yu is a standout example because it augments Whimsicott's modest damage output with Beads of Ruin. Other setup Pokemon that enjoy Encore are especially useful to justify using Whimsicott on a team over Tornadus, including Calm Mind Raging Bolt, Swords Dance Ogerpon-H, and Nasty Plot Gholdengo. It's important to make sure Whimsicott has teammates that can deal with problematic Dark-types like Chi-Yu, Ting-Lu, and Kingambit due to their Prankster immunity, and a Fighting-type like Urshifu-R or Iron Hands can help with that significantly.