Suppose the following case:
Salamance used Draco Meteor with Z-crystal.
Oranguru used Instruct to point to the Salamance.
In this case, does Instruct point to Draco Meteor, or one more Z-move, or end up in a failure?
From my own personal experience, Instruct fails when used on a partner who just used a Z-move.
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Instruct will fail if the target has not made any move, is in the middle of Bide, Focus Punch, Beak Blast, Shell Trap, or a consecutively executed move, or when the instructed move's PP is depleted. It will also fail if the target's most recent move is Instruct itself, Bide, Focus Punch, Beak Blast, Shell Trap, Struggle, a move that requires recharging (such as Hyper Beam), a move with a charging turn (such as Dig or Skull Bash), a move that calls another move (such as Metronome), or a Z-Move.