Whimsicott's ability Prankster allows it to act as a reliable support Pokemon. Its wide supporting movepool complements this well, featuring moves such as Tailwind, Encore, Safeguard, Taunt, and Grass Whistle. This variety of options makes Whimsicott fairly unpredictable; however, this also makes it suffer from four-moveslot syndrome, meaning it is forced to leave out some important moves and adapt its set depending on the team's needs. Whimsicott has a mediocre typing: it is weak to attacks coming from common Pokemon such as Primal Groudon and Mega Rayquaza, but it also resists types such as Water and Dark and is immune to Dragon, giving it a small advantage over threats such as Primal Kyogre, Yveltal, and most Dragons if played correctly. However, most of these Pokemon have a way of hitting Whimsicott super effectively, via either a secondary STAB move or a coverage move. Whimsicott's Grass typing also makes it immune to a common redirection move in Rage Powder, making it a great answer to Amoonguss. Whimsicott's bulk is very low, though, and doesn't allow it to provide any significant defensive presence, although Focus Sash somewhat makes up for this. As any other support Pokemon, Whimsicott is entirely reliant on its teammates, has little offensive presence, and can hardly win if it is the last Pokemon left on the field.
move 1: Tailwind
move 2: Encore
move 3: Moonblast / Endeavor
move 4: Protect / Safeguard / Taunt
item: Focus Sash
evs: 252 HP / 4 Def / 252 Spe
Tailwind doubles Whimsicott's and its teammates' Speed, and Prankster ensures it is set up safely. Encore locks the foe into a move, ideally a status one, preventing it from being useful for the following three turns. It is particularly helpful to deal with Protect users, Fake Out users such as Mega Kangaskhan, Geomancy Xerneas, and most Trick Room and Tailwind setters. Moonblast is a reliable STAB move that hits the likes of Mega Rayquaza and Yveltal super effectively. The Special Attack drop chance can be useful too. Endeavor pairs well with Focus Sash, being able to bring the foe down to 1 HP after Whimsicott has been hit by a move that would otherwise KO it. Protect scouts for the foes' moves and stalls out Trick Room. Safeguard can be used to prevent Whimsicott's team from being inflicted with status, and it is especially useful against Smeargle, one of the most common leads. Alternatively, Taunt can prevent the foes from using their own status moves and can prevent sweepers, such as Geomancy Xerneas, from setting up.
252 Speed EVs and a Timid nature maximize Whimsicott's already excellent Speed. Maximum HP investment alongside 4 Defense EVs increases Whimsicott's overall bulk, though it still doesn't allow Whimsicott to tank repeated attacks. Prankster gives priority to any of Whimsicott's non-attacking moves, allowing it to act before faster threats such as Talonflame and Mewtwo and turning it into an incredible supportive Pokemon. Focus Sash allows Whimsicott to survive at least one hit, ensuring it either sets up Tailwind or uses Encore successfully.
Whimsicott should almost always be used as a lead in order to set up Tailwind as soon as possible and gain an early advantage for its teammates. Furthermore, Whimsicott has a decent matchup against common leads such as Smeargle and Crobat, since it can lock them into their status moves thanks to Encore or prevent them from using status moves with Taunt. Whimsicott does not have much offensive presence, but a well-timed Endeavor after it has been brought down to 1 HP in conjunction with minimal offensive support from its partner can KO most common threats such as Primal Groudon, Primal Kyogre, and Mega Rayquaza.
Powerful wallbreakers such as Primal Kyogre, Mega Rayquaza, and Primal Groudon make for excellent partners, as they can take advantage of Tailwind to quickly weaken the opposing team. In particular, Pokemon with powerful spread moves such as Primal Kyogre's Origin Pulse make for especially good teammates, as Whimsicott's Encore will often force switches, and few Pokemon are not 2HKOed by such powerful attacks. Setup sweepers such as Swords Dance Primal Groudon, Swords Dance Rayquaza, and Geomancy Xerneas can take advantage of the free turns provided by Encore to set up more easily, and they can also rely on an immunity to status thanks to Safeguard, if Whimsicott is running it. Fake Out users, most notably Mega Kangaskhan, can form a leading duo with Whimsicott, which appreciates being able to set up Tailwind with much less pressure. Mega Gengar can trap a foe affected by Encore and use Disable on it, effectively rendering it completely useless.
Grass Knot can be used as an alternative attacking option, as it reaches its full power against common threats such as Primal Kyogre and Primal Groudon, dealing significant damage to them. Grass Whistle can be considered because it has priority thanks to Prankster, although its awful accuracy makes it not worth using in most cases. Swagger can be used in conjunction with Safeguard in order to give a physically attacking partner a free boost in Attack. Beat Up works well if Whimsicott is paired with Terrakion, as the move can boost the latter's Attack to sky-high levels without damaging it significantly. Worry Seed is a viable option to negate key abilities such as Mega Kangaskhan's Parental Bond, Mega Salamence's Aerilate, Cresselia's Levitate, and Primal Groudon's Desolate Land. Trick Room is an option if Whimsicott is used on dedicated Trick Room teams, and the loss of Whimsicott's Speed advantage is inconsequential, since it will use moves with priority most of the times. Whimsicott can further aid its partner with Helping Hand, and the combination of Prankster and Focus Sash ensures that almost nothing can stop it from using the move; this can be particularly dangerous considering the high number of powerful moves in the tier. Mental Herb can be used instead of a Focus Sash to avoid being Taunted one time, though very few Pokemon can Taunt Whimsicott if it chooses to use a priority status move.
Checks and Counters
**Mega Kangaskhan**: Mega Kangaskhan's access to Parental Bond renders Whimsicott's Focus Sash useless. However, it must be wary of getting locked into Fake Out.
**Trick Room **: Trick Room nullifies Tailwind's Speed boost, and most Trick Room setters, such as Cresselia and Bronzong, run Mental Herb, so Taunt will not be useful against them. However, Whimsicott can use priority Encore the following turn to lock them into the same move.
**Priority Attacks**: Talonflame's higher Speed means that it can use Brave Bird before getting locked into Tailwind by Encore and proceed to KO Whimsicott without trouble. Furthermore, Talonflame's Fire / Flying typing makes it take almost no damage from any of Whimsicott's attacking moves. Rayquaza has access to Extreme Speed, which has higher priority than any of Whimsicott's moves; however, it has to be wary of Moonblast.
**Spread Move Users**: Attackers with spread moves, such as Primal Groudon, Primal Kyogre, Xerneas, and Mega Salamence, are particularly troublesome, as they make it much easier to deal with Whimsicott's Focus Sash.
**Taunt**: If Whimsicott gets Taunted, it is forced to either stay on the field and provide little utility or switch out, potentially making a teammate take an unwanted hit.