diff --git a/PkmnLib.Dynamic/Models/LearnedMove.cs b/PkmnLib.Dynamic/Models/LearnedMove.cs
index 490d323..532ceda 100644
--- a/PkmnLib.Dynamic/Models/LearnedMove.cs
+++ b/PkmnLib.Dynamic/Models/LearnedMove.cs
@@ -42,6 +42,11 @@ public enum MoveLearnMethod
     /// The move is learned by using a move sketch.
     /// </summary>
     Sketch,
+
+    /// <summary>
+    /// The move is temporarily copied through Mimic.
+    /// </summary>
+    Mimic,
 }
 
 /// <summary>
diff --git a/PkmnLib.Dynamic/Models/Pokemon.cs b/PkmnLib.Dynamic/Models/Pokemon.cs
index cbc26e7..a24735b 100644
--- a/PkmnLib.Dynamic/Models/Pokemon.cs
+++ b/PkmnLib.Dynamic/Models/Pokemon.cs
@@ -167,10 +167,18 @@ public interface IPokemon : IScriptSource, IDeepCloneable
 
     /// <summary>
     /// The moves the Pokemon has learned. This is of a set length of <see cref="Const.MovesCount"/>. Empty move slots
-    /// are null.
+    /// are null. If a move slot is temporarily replaced (see <see cref="LearnTemporaryMove"/>), this shows the
+    /// replacement move.
     /// </summary>
     IReadOnlyList<ILearnedMove?> Moves { get; }
 
+    /// <summary>
+    /// The permanently learned moves of the Pokemon, ignoring any temporary replacements made through
+    /// <see cref="LearnTemporaryMove"/>. This is of a set length of <see cref="Const.MovesCount"/>. Empty move
+    /// slots are null.
+    /// </summary>
+    IReadOnlyList<ILearnedMove?> BaseMoves { get; }
+
     /// <summary>
     /// Checks whether the Pokemon has a specific move in its current moveset.
     /// </summary>
@@ -181,6 +189,14 @@ public interface IPokemon : IScriptSource, IDeepCloneable
     /// </summary>
     void SwapMoves(byte index1, byte index2);
 
+    /// <summary>
+    /// Temporarily replaces the move in the given slot until the Pokemon leaves the battlefield. The permanently
+    /// learned move in the slot is left untouched and becomes visible again automatically. Used by effects such as
+    /// Mimic.
+    /// </summary>
+    /// <exception cref="KeyNotFoundException">Thrown when the move is not found in the move library.</exception>
+    void LearnTemporaryMove(StringKey moveName, MoveLearnMethod method, byte index);
+
     /// <summary>
     /// Whether or not the Pokemon is allowed to gain experience.
     /// </summary>
@@ -772,8 +788,19 @@ public class PokemonImpl : ScriptSource, IPokemon
 
     private readonly ILearnedMove?[] _learnedMoves = new ILearnedMove[Const.MovesCount];
 
+    /// <summary>
+    /// Battle-only per-slot overrides of <see cref="_learnedMoves"/>. The permanent moveset is never mutated by
+    /// temporary moves; discarding this array is all that is needed to restore the original moves.
+    /// </summary>
+    private ILearnedMove?[]? _temporaryMoves;
+
     /// <inheritdoc />
-    public IReadOnlyList<ILearnedMove?> Moves => _learnedMoves;
+    public IReadOnlyList<ILearnedMove?> Moves => _temporaryMoves == null
+        ? _learnedMoves
+        : _temporaryMoves.Select((move, index) => move ?? _learnedMoves[index]).ToArray();
+
+    /// <inheritdoc />
+    public IReadOnlyList<ILearnedMove?> BaseMoves => _learnedMoves;
 
     /// <inheritdoc />
     public bool HasMove(StringKey moveName) => Moves.Any(move => move?.MoveData.Name == moveName);
@@ -783,10 +810,9 @@ public class PokemonImpl : ScriptSource, IPokemon
     {
         if (index1 >= Const.MovesCount || index2 >= Const.MovesCount)
             return;
-        var move1 = _learnedMoves[index1];
-        var move2 = _learnedMoves[index2];
-        _learnedMoves[index1] = move2;
-        _learnedMoves[index2] = move1;
+        (_learnedMoves[index1], _learnedMoves[index2]) = (_learnedMoves[index2], _learnedMoves[index1]);
+        if (_temporaryMoves != null)
+            (_temporaryMoves[index1], _temporaryMoves[index2]) = (_temporaryMoves[index2], _temporaryMoves[index1]);
     }
 
     /// <inheritdoc />
@@ -1286,6 +1312,18 @@ public class PokemonImpl : ScriptSource, IPokemon
         _learnedMoves[index] = new LearnedMoveImpl(move, method);
     }
 
+    /// <inheritdoc />
+    public void LearnTemporaryMove(StringKey moveName, MoveLearnMethod method, byte index)
+    {
+        if (index >= Const.MovesCount)
+            throw new ArgumentOutOfRangeException(nameof(index), $"Move slot {index} is out of range.");
+        if (!Library.StaticLibrary.Moves.TryGet(moveName, out var move))
+            throw new KeyNotFoundException($"Move {moveName} not found.");
+
+        _temporaryMoves ??= new ILearnedMove?[Const.MovesCount];
+        _temporaryMoves[index] = new LearnedMoveImpl(move, method);
+    }
+
     /// <inheritdoc />
     public bool HasStatus(StringKey status) => StatusScript.Script?.Name == status;
 
@@ -1367,6 +1405,7 @@ public class PokemonImpl : ScriptSource, IPokemon
             if (!onBattleField)
             {
                 Volatile.Clear();
+                _temporaryMoves = null;
                 HeightInMeters = Form.Height;
                 Types = Form.Types;
                 OverrideAbility = null;
@@ -1388,6 +1427,7 @@ public class PokemonImpl : ScriptSource, IPokemon
         var battleData = BattleData;
         BattleData = null;
         Volatile.Clear();
+        _temporaryMoves = null;
         HeightInMeters = Form.Height;
         Types = Form.Types;
         OverrideAbility = null;
diff --git a/PkmnLib.Dynamic/Models/Serialized/SerializedPokemon.cs b/PkmnLib.Dynamic/Models/Serialized/SerializedPokemon.cs
index 5743e6d..8bcaef7 100644
--- a/PkmnLib.Dynamic/Models/Serialized/SerializedPokemon.cs
+++ b/PkmnLib.Dynamic/Models/Serialized/SerializedPokemon.cs
@@ -33,7 +33,7 @@ public record SerializedPokemon
         Nature = pokemon.Nature.Name;
         Nickname = pokemon.Nickname;
         Ability = pokemon.Form.GetAbility(pokemon.AbilityIndex);
-        Moves = pokemon.Moves.Select(move =>
+        Moves = pokemon.BaseMoves.Select(move =>
         {
             if (move == null)
                 return null;
diff --git a/PkmnLib.Tests/Dynamic/PokemonTemporaryMoveTests.cs b/PkmnLib.Tests/Dynamic/PokemonTemporaryMoveTests.cs
new file mode 100644
index 0000000..3deec7c
--- /dev/null
+++ b/PkmnLib.Tests/Dynamic/PokemonTemporaryMoveTests.cs
@@ -0,0 +1,82 @@
+using PkmnLib.Dynamic.Models;
+using PkmnLib.Static;
+using PkmnLib.Static.Species;
+using PkmnLib.Tests.Integration;
+
+namespace PkmnLib.Tests.Dynamic;
+
+/// <summary>
+/// Tests for the temporary move overlay (<see cref="IPokemon.LearnTemporaryMove"/>), used by effects such as
+/// Mimic. The permanently learned moves must never be mutated by a temporary move, and the overlay must be
+/// discarded by the engine itself when the Pokemon leaves the battlefield.
+/// </summary>
+public class PokemonTemporaryMoveTests
+{
+    private static IPokemon CreatePokemon()
+    {
+        var library = LibraryHelpers.LoadLibrary();
+        if (!library.StaticLibrary.Species.TryGet("bulbasaur", out var species))
+            throw new InvalidOperationException("Failed to load bulbasaur species.");
+        var pokemon = new PokemonImpl(library, species, species.GetDefaultForm(), new AbilityIndex
+        {
+            Index = 0,
+            IsHidden = false,
+        }, 50, 0, Gender.Male, 0, "hardy");
+        pokemon.LearnMove("tackle", MoveLearnMethod.LevelUp, 0);
+        return pokemon;
+    }
+
+    [Test]
+    public async Task LearnTemporaryMove_ReplacesMoveInMovesButNotInBaseMoves()
+    {
+        var pokemon = CreatePokemon();
+
+        pokemon.LearnTemporaryMove("swords_dance", MoveLearnMethod.Mimic, 0);
+
+        await Assert.That(pokemon.Moves[0]!.MoveData.Name.ToString()).IsEqualTo("swords_dance");
+        await Assert.That(pokemon.Moves[0]!.LearnMethod).IsEqualTo(MoveLearnMethod.Mimic);
+        await Assert.That(pokemon.BaseMoves[0]!.MoveData.Name.ToString()).IsEqualTo("tackle");
+    }
+
+    [Test]
+    public async Task SetOnBattlefield_LeavingField_RestoresOriginalMoveWithItsPP()
+    {
+        var pokemon = CreatePokemon();
+        pokemon.SetBattleData(Substitute.For<IBattle>(), 0);
+        pokemon.SetOnBattlefield(true);
+
+        // Use the original move once, so we can verify its PP survives the temporary replacement untouched.
+        var originalMove = pokemon.Moves[0]!;
+        originalMove.TryUse();
+        var expectedPp = originalMove.CurrentPp;
+
+        pokemon.LearnTemporaryMove("swords_dance", MoveLearnMethod.Mimic, 0);
+        pokemon.SetOnBattlefield(false);
+
+        await Assert.That(ReferenceEquals(pokemon.Moves[0], originalMove)).IsTrue();
+        await Assert.That(pokemon.Moves[0]!.CurrentPp).IsEqualTo(expectedPp);
+    }
+
+    [Test]
+    public async Task ClearBattleData_RestoresOriginalMove()
+    {
+        var pokemon = CreatePokemon();
+        pokemon.SetBattleData(Substitute.For<IBattle>(), 0);
+        pokemon.LearnTemporaryMove("swords_dance", MoveLearnMethod.Mimic, 0);
+
+        pokemon.ClearBattleData();
+
+        await Assert.That(pokemon.Moves[0]!.MoveData.Name.ToString()).IsEqualTo("tackle");
+    }
+
+    [Test]
+    public async Task Serialize_WithActiveTemporaryMove_WritesOriginalMove()
+    {
+        var pokemon = CreatePokemon();
+        pokemon.LearnTemporaryMove("swords_dance", MoveLearnMethod.Mimic, 0);
+
+        var serialized = pokemon.Serialize();
+
+        await Assert.That(serialized.Moves[0]!.MoveName.ToString()).IsEqualTo("tackle");
+    }
+}
\ No newline at end of file
diff --git a/Plugins/PkmnLib.Plugin.Gen7.Tests/Scripts/Moves/MimicTests.cs b/Plugins/PkmnLib.Plugin.Gen7.Tests/Scripts/Moves/MimicTests.cs
index c0fc2bc..f511182 100644
--- a/Plugins/PkmnLib.Plugin.Gen7.Tests/Scripts/Moves/MimicTests.cs
+++ b/Plugins/PkmnLib.Plugin.Gen7.Tests/Scripts/Moves/MimicTests.cs
@@ -15,10 +15,6 @@ namespace PkmnLib.Plugin.Gen7.Tests.Scripts.Moves;
 /// </summary>
 public class MimicTests
 {
-    private const string NotImplementedReason =
-        "Mimic is not implemented: Mimic.cs contains only a FIXME comment and implements no script hooks, so " +
-        "the move has no effect (Bulbapedia: 'Mimic copies a move from the target')";
-
     /// <summary>
     /// Creates a mocked <see cref="ILearnedMove"/> whose move data has the given name.
     /// </summary>
@@ -46,9 +42,12 @@ public class MimicTests
         move.GetHitData(target, 0).Returns(hitData);
 
         // The user knows another move in slot 0, and Mimic in slot 1; Mimic is the chosen move.
+        // The moves are created before the Returns call, as creating substitutes inside Returns arguments
+        // resets NSubstitute's last-call tracking.
         var mimicMove = CreateLearnedMove("mimic");
         move.ChosenMove.Returns(mimicMove);
-        user.Moves.Returns(new[] { CreateLearnedMove(userOtherMove), mimicMove });
+        var userMoves = new[] { CreateLearnedMove(userOtherMove), mimicMove };
+        user.Moves.Returns(userMoves);
 
         var battleData = Substitute.For<IPokemonBattleData>();
         if (targetLastUsedMove != null)
@@ -85,11 +84,11 @@ public class MimicTests
         hitData.ReceivedCalls().Any(c => c.GetMethodInfo().Name == "Fail");
 
     /// <summary>
-    /// Helper to extract the arguments of the user's received <see cref="IPokemon.LearnMove"/> call.
+    /// Helper to extract the arguments of the user's received <see cref="IPokemon.LearnTemporaryMove"/> call.
     /// </summary>
     private static (StringKey moveName, byte index)? GetLearnedMove(IPokemon user)
     {
-        var call = user.ReceivedCalls().FirstOrDefault(c => c.GetMethodInfo().Name == "LearnMove");
+        var call = user.ReceivedCalls().FirstOrDefault(c => c.GetMethodInfo().Name == "LearnTemporaryMove");
         if (call == null)
             return null;
         return ((StringKey)call.GetArguments()[0]!, (byte)call.GetArguments()[2]!);
@@ -100,7 +99,7 @@ public class MimicTests
     /// place" and (Generation II onwards) "Mimic now copies the target's last used move."
     /// The target's last used move must be learned in the move slot that holds Mimic.
     /// </summary>
-    [Test, TestFailing(NotImplementedReason)]
+    [Test]
     public async Task OnSecondaryEffect_TargetUsedMove_UserLearnsTargetsLastMoveInMimicsSlot()
     {
         // Arrange
@@ -121,7 +120,7 @@ public class MimicTests
     /// Bulbapedia: (Generation II onwards) "Mimic now copies the target's last used move."
     /// If the target has not used a move yet, there is nothing to copy and the hit must fail.
     /// </summary>
-    [Test, TestFailing(NotImplementedReason)]
+    [Test]
     public async Task OnSecondaryEffect_TargetHasNotUsedAMove_FailsHit()
     {
         // Arrange
@@ -141,8 +140,8 @@ public class MimicTests
     /// Metronome, or any move the user already knows.", (Generation IV onwards) "Mimic will fail to copy
     /// Chatter.", and (Generation V onwards) "Mimic is no longer able to copy Transform."
     /// </summary>
-    [Test, TestFailing(NotImplementedReason), Arguments("sketch"), Arguments("transform"), Arguments("struggle"),
-     Arguments("metronome"), Arguments("chatter")]
+    [Test, Arguments("sketch"), Arguments("transform"), Arguments("struggle"), Arguments("metronome"),
+     Arguments("chatter")]
     public async Task OnSecondaryEffect_TargetsLastMoveIsUncopyable_FailsHit(string uncopyableMove)
     {
         // Arrange
@@ -160,7 +159,7 @@ public class MimicTests
     /// <summary>
     /// Bulbapedia: (Generation II onwards) "It now fails to copy ... any move the user already knows."
     /// </summary>
-    [Test, TestFailing(NotImplementedReason)]
+    [Test]
     public async Task OnSecondaryEffect_UserAlreadyKnowsTargetsLastMove_FailsHit()
     {
         // Arrange
@@ -175,4 +174,22 @@ public class MimicTests
         await Assert.That(ReceivedFail(hitData)).IsTrue();
         await Assert.That(GetLearnedMove(user).HasValue).IsFalse();
     }
+
+    /// <summary>
+    /// Bulbapedia: (Generation II onwards) "The copied move will also only have 5 PP".
+    /// After learning the copy, its current PP must be set to 5.
+    /// </summary>
+    [Test]
+    public async Task OnSecondaryEffect_TargetUsedMove_CopiedMoveGetsFivePP()
+    {
+        // Arrange
+        var mimic = await GetSecondaryEffectHook();
+        var (move, user, target, _) = CreateTestSetup("tackle");
+
+        // Act
+        mimic.OnSecondaryEffect(move, target, 0);
+
+        // Assert - the move in Mimic's slot (slot 1) has its PP set to 5.
+        user.Moves[1]!.Received(1).SetCurrentPP(5);
+    }
 }
\ No newline at end of file
diff --git a/Plugins/PkmnLib.Plugin.Gen7/Scripts/Moves/Mimic.cs b/Plugins/PkmnLib.Plugin.Gen7/Scripts/Moves/Mimic.cs
index 761caf9..6596546 100644
--- a/Plugins/PkmnLib.Plugin.Gen7/Scripts/Moves/Mimic.cs
+++ b/Plugins/PkmnLib.Plugin.Gen7/Scripts/Moves/Mimic.cs
@@ -1,7 +1,43 @@
+using PkmnLib.Plugin.Gen7.Scripts.Utils;
+
 namespace PkmnLib.Plugin.Gen7.Scripts.Moves;
 
+/// <summary>
+/// Mimic copies the target's last used move into the move slot Mimic occupies, with 5 PP, until the user
+/// leaves the field. It fails if the target has not used a move, if that move is Sketch, Transform, Struggle,
+/// Metronome, or Chatter, or if the user already knows it.
+///
+/// <see href="https://bulbapedia.bulbagarden.net/wiki/Mimic_(move)">Bulbapedia - Mimic</see>
+/// </summary>
 [Script(ScriptCategory.Move, "mimic")]
-public class Mimic : Script
+public class Mimic : Script, IScriptOnSecondaryEffect
 {
-    // FIXME: support for temporarily copying moves to a move slot.
+    /// <inheritdoc />
+    public void OnSecondaryEffect(IExecutingMove move, IPokemon target, byte hit)
+    {
+        var moveSlot = move.User.Moves.IndexOf(move.ChosenMove);
+        if (moveSlot == -1)
+        {
+            move.GetHitData(target, hit).Fail();
+            return;
+        }
+
+        var lastMove = target.BattleData?.LastMoveChoice;
+        if (lastMove == null || !lastMove.ChosenMove.MoveData.CanCopyMove())
+        {
+            move.GetHitData(target, hit).Fail();
+            return;
+        }
+
+        var copiedMoveName = lastMove.ChosenMove.MoveData.Name;
+        if (move.User.Moves.Any(m => m?.MoveData.Name == copiedMoveName))
+        {
+            move.GetHitData(target, hit).Fail();
+            return;
+        }
+
+        move.User.LearnTemporaryMove(copiedMoveName, MoveLearnMethod.Mimic, (byte)moveSlot);
+        // The copied move only has 5 PP, or its own maximum PP if that is lower.
+        move.User.Moves[moveSlot]?.SetCurrentPP(5);
+    }
 }
\ No newline at end of file