What it does
Instruct is a Normal-type status move that deals no damage. The target immediately uses the last move it selected — as an extra action, independent of its normal turn. That means the target can act twice in one turn: once normally, once from Instruct. PP is deducted for both uses.
The key detail in doubles: Instruct can target any Pokémon on the field, including your own partner. Competitive play almost exclusively uses it this way — point it at your ally, get their move off twice in one turn.
Constraints: the target must have used a move the previous turn; that move must have PP remaining; moves currently charging or recharging cannot be repeated. Disabled moves can be Instructed, and Encore's restrictions are bypassed.
Who runs it
Oranguru runs Instruct at 98% — it is functionally the exclusive user of this move in competitive play. Oranguru is slow, but that's fine: its entire value is in giving a partner a free second action. Its role is less about what it does and more about what it lets its partner do twice.
How to use it
The standard setup: partner uses a spread move that hits both opponents, then Instruct makes them use it again. Both opposing Pokémon take the spread move twice in one turn, while your own Pokémon are free to do something else. That's four hits of damage in one round from two Pokémon.
It also works with single-target nukes. If your partner has a target in range but can't KO it in one hit, Instruct on the same turn can push the combined damage over the threshold — two hits instead of one, same target, same turn.
Trick Room interacts unusually: if your partner used Trick Room last turn and you Instruct it again, Trick Room triggers a second time. If Trick Room is already active, this cancels it. That's a real tool for managing the board state when you need Trick Room gone without using a different move slot.
Tips & strategy
Instruct fails if the target has no previous move on record — switches, Pokémon that haven't acted yet, or targets whose last move was a protection move all leave you with nothing. Build that into your plan before committing a turn.
Speed management is the other half of running Oranguru. For Instruct to work cleanly, you usually want Oranguru to move after its partner — that way the partner has a 'last move' for Instruct to reference. Oranguru's low speed handles this naturally in most situations. Under Trick Room the order flips: Oranguru acts first, partner acts after, and the partner's normal action that turn counts as the 'last move' for any future Instruct on the following turn.
PP depletion is a real concern in longer games. Every Instruct trigger costs PP on your partner's move. If your partner is running a move with low PP and you're spamming Instruct, you can run dry before the game ends. Track the PP count and save Instruct for the turns that matter.