It's a fair question, and it comes up every season: Taunt looks incredible on Whimsicott. Prankster gives it priority, so a turn-one Taunt can shut down Trick Room, stop Perish Song, and lock a mirror Whimsicott into doing nothing but clicking Moonblast. It's a question the community keeps asking — why isn't Taunt standard? — and the answer is more interesting than a flat yes or no.
The problem isn't that Taunt is bad. It's that Whimsicott only has four slots, and three of them are close to locked. Most builds run Protect (Whimsicott is almost always holding a Focus Sash, and Protect preserves it), Tailwind (the whole reason it's on your team), and Moonblast (so it isn't completely passive). That leaves exactly one flexible slot — and the field is crowded.
The consensus killer is Encore. Nearly every experienced player makes the same point: Encore does much of what Taunt does, and more. Both can neuter a Trick Room setter, but Encore can also lock an opponent into a bad move, force switches, and punish setup rather than just prevent it. As one player put it, "Taunt prevents a passive turn; Encore punishes a passive turn." In a best-of-one ladder environment, the move that generates tempo and denies it wins the slot.
Taunt also runs into a wall of immunities. The Pokémon you'd most want to Taunt tend to be immune or unreachable: Sableye and Grimmsnarl are Dark-types and ignore Prankster status, Farigiraf blocks it with Armor Tail, Aromatisse has Aroma Veil, and mirror Whimsicotts come down to a speed tie you'd often rather not gamble on. Against redirection users like Sinistcha, Taunt isn't fast enough to matter on the turn it needs to. The list of clean, high-value Taunt targets is shorter than it looks.
Interestingly, there's a spicier alternative that several strong players prefer for the flex slot: Worry Seed. Removing an opponent's ability — shutting off a Mega's gimmick, stopping Archaludon from snowballing, cutting Basculegion's damage, or neutralising a Prankster mon — was described as paying "massive dividends" in a format defined by ability-reliant threats.
So does Taunt deserve the slot? The honest answer is almost. It's a genuinely good, matchup-specific tech — especially into Trick Room and Perish teams — and a handful of laddering players run it happily. But as a default, it loses to Encore's flexibility and gets walled by too many common immunities. Keep it in your back pocket as a targeted call, not your standard fourth move.
Want to see what else Whimsicott can learn before you lock a set? Its full movepool is in the Pokémon database.