diff --git a/PKHeX.Core/Editing/IBattleTemplate.cs b/PKHeX.Core/Editing/IBattleTemplate.cs
index 1fa1577e1..c91c5a80e 100644
--- a/PKHeX.Core/Editing/IBattleTemplate.cs
+++ b/PKHeX.Core/Editing/IBattleTemplate.cs
@@ -53,7 +53,7 @@ public interface IBattleTemplate : ISpeciesForm, IGigantamaxReadOnly, IDynamaxLe
     /// <summary>
     /// <see cref="PKM.HPType"/> of the Set entity.
     /// </summary>
-    int HiddenPowerType { get; }
+    sbyte HiddenPowerType { get; }
 
     /// <summary>
     /// <see cref="EffortValues"/> of the Set entity.
diff --git a/PKHeX.Core/Editing/Showdown/ShowdownSet.cs b/PKHeX.Core/Editing/Showdown/ShowdownSet.cs
index 1229f71e5..0fd1e6e4f 100644
--- a/PKHeX.Core/Editing/Showdown/ShowdownSet.cs
+++ b/PKHeX.Core/Editing/Showdown/ShowdownSet.cs
@@ -68,7 +68,7 @@ public sealed class ShowdownSet : IBattleTemplate
     public int[] IVs { get; } = [31, 31, 31, 31, 31, 31];
 
     /// <inheritdoc/>
-    public int HiddenPowerType { get; private set; } = -1;
+    public sbyte HiddenPowerType { get; private set; } = -1;
 
     public MoveType TeraType { get; private set; } = MoveType.Any;
 
@@ -512,7 +512,7 @@ public ShowdownSet(PKM pk)
         var moves = Moves.AsSpan();
         pk.GetMoves(moves);
         if (moves.Contains((ushort)Move.HiddenPower))
-            HiddenPowerType = HiddenPower.GetType(IVs, Context);
+            HiddenPowerType = (sbyte)HiddenPower.GetType(IVs, Context);
 
         Nature = pk.StatNature;
         Gender = pk.Gender < 2 ? pk.Gender : (byte)2;
@@ -719,7 +719,7 @@ private ReadOnlySpan<char> ParseLineMove(ReadOnlySpan<char> line)
         if (hpVal == -1)
             return hiddenPowerName;
 
-        HiddenPowerType = hpVal;
+        HiddenPowerType = (sbyte)hpVal;
         if (!Array.TrueForAll(IVs, z => z == 31))
         {
             if (!HiddenPower.SetIVsForType(hpVal, IVs, Context))
diff --git a/PKHeX.Core/Legality/Encounters/Generator/EncounterCriteria.cs b/PKHeX.Core/Legality/Encounters/Generator/EncounterCriteria.cs
index 40fe6336d..48788258b 100644
--- a/PKHeX.Core/Legality/Encounters/Generator/EncounterCriteria.cs
+++ b/PKHeX.Core/Legality/Encounters/Generator/EncounterCriteria.cs
@@ -14,8 +14,8 @@ public sealed record EncounterCriteria : IFixedNature, IFixedAbilityNumber, IShi
     public static readonly EncounterCriteria Unrestricted = new();
 
     /// <summary> End result's gender. </summary>
-    /// <remarks> Leave as null to not restrict gender. </remarks>
-    public byte? Gender { get; init; }
+    /// <remarks> Leave as <see cref="Gender.Random"/> to not restrict gender. </remarks>
+    public Gender Gender { get; init; } = Gender.Random;
 
     /// <summary> End result's ability numbers permitted. </summary>
     /// <remarks> Leave as <see cref="Any12H"/> to not restrict ability. </remarks>
@@ -29,12 +29,12 @@ public sealed record EncounterCriteria : IFixedNature, IFixedAbilityNumber, IShi
     /// <remarks> Leave as <see cref="Shiny.Random"/> to not restrict shininess. </remarks>
     public Shiny Shiny { get; init; }
 
-    public int IV_HP  { get; init; } = RandomIV;
-    public int IV_ATK { get; init; } = RandomIV;
-    public int IV_DEF { get; init; } = RandomIV;
-    public int IV_SPA { get; init; } = RandomIV;
-    public int IV_SPD { get; init; } = RandomIV;
-    public int IV_SPE { get; init; } = RandomIV;
+    public sbyte IV_HP  { get; init; } = RandomIV;
+    public sbyte IV_ATK { get; init; } = RandomIV;
+    public sbyte IV_DEF { get; init; } = RandomIV;
+    public sbyte IV_SPA { get; init; } = RandomIV;
+    public sbyte IV_SPD { get; init; } = RandomIV;
+    public sbyte IV_SPE { get; init; } = RandomIV;
 
     /// <summary>
     /// If the Encounter yields variable level ranges (e.g. RNG correlation), force the minimum level instead of yielding first match.
@@ -44,7 +44,7 @@ public sealed record EncounterCriteria : IFixedNature, IFixedAbilityNumber, IShi
     public sbyte TeraType { get; init; } = -1;
 
     // unused
-    public int HPType { get; init; } = -1;
+    public sbyte HPType { get; init; } = -1;
 
     private const int RandomIV = -1;
 
@@ -102,12 +102,12 @@ public static EncounterCriteria GetCriteria(IBattleTemplate s, IPersonalTable t)
     public static EncounterCriteria GetCriteria(IBattleTemplate s, IPersonalInfo pi) => new()
     {
         Gender = GetGenderPermissions(s.Gender, pi),
-        IV_HP = s.IVs[0],
-        IV_ATK = s.IVs[1],
-        IV_DEF = s.IVs[2],
-        IV_SPE = s.IVs[3],
-        IV_SPA = s.IVs[4],
-        IV_SPD = s.IVs[5],
+        IV_HP  = (sbyte)s.IVs[0],
+        IV_ATK = (sbyte)s.IVs[1],
+        IV_DEF = (sbyte)s.IVs[2],
+        IV_SPE = (sbyte)s.IVs[3],
+        IV_SPA = (sbyte)s.IVs[4],
+        IV_SPD = (sbyte)s.IVs[5],
         HPType = s.HiddenPowerType,
 
         Ability = GetAbilityPermissions(s.Ability, pi),
@@ -116,14 +116,14 @@ public static EncounterCriteria GetCriteria(IBattleTemplate s, IPersonalInfo pi)
         TeraType = (sbyte)s.TeraType,
     };
 
-    private static byte? GetGenderPermissions(byte? gender, IGenderDetail pi)
+    private static Gender GetGenderPermissions(byte? gender, IGenderDetail pi)
     {
         if (gender is not <= 1)
-            return null;
+            return Gender.Random;
         if (pi.IsDualGender)
-            return gender;
+            return (Gender)gender;
         var g = pi.FixedGender();
-        return g <= 1 ? g : null;
+        return g <= 1 ? (Gender)g : Gender.Random;
     }
 
     private static AbilityPermission GetAbilityPermissions(int ability, IPersonalAbility pi)
@@ -169,12 +169,12 @@ public Nature GetNature()
     /// <summary>
     /// Indicates if the <see cref="Gender"/> is specified.
     /// </summary>
-    public bool IsGenderSpecified => Gender != null;
+    public bool IsGenderSpecified => Gender != Gender.Random;
 
     /// <summary>
     /// Indicates if the requested gender matches the criteria.
     /// </summary>
-    public bool IsGenderSatisfied(byte gender) => !IsGenderSpecified || gender == Gender;
+    public bool IsGenderSatisfied(byte gender) => !IsGenderSpecified || (Gender)gender == Gender;
 
     /// <summary>
     /// Gets the gender to generate, random if unspecified by the template or criteria.
@@ -189,7 +189,7 @@ public byte GetGender(byte gender, IGenderDetail pkPersonalInfo)
     /// <inheritdoc cref="GetGender(byte, IGenderDetail)"/>
     public byte GetGender(Gender gender, IGenderDetail pkPersonalInfo)
     {
-        if (gender == Core.Gender.Random)
+        if (gender == Gender.Random)
             return GetGender(pkPersonalInfo);
         return (byte)gender;
     }
@@ -203,8 +203,8 @@ public byte GetGender(IGenderDetail pkPersonalInfo)
             return pkPersonalInfo.FixedGender();
         if (pkPersonalInfo.Genderless)
             return 2;
-        if (Gender is {  } request and (0 or 1))
-            return request;
+        if (Gender is not Gender.Random)
+            return (byte)Gender;
         return pkPersonalInfo.RandomGender();
     }
 
@@ -356,4 +356,10 @@ public bool IsCompatibleIVs(ReadOnlySpan<int> ivs)
             return false;
         return true;
     }
+
+    public void GetCombinedIVs(out uint iv1, out uint iv2)
+    {
+        iv1 = (byte)IV_HP | (uint)IV_ATK << 5 | (uint)IV_DEF << 10;
+        iv2 = (byte)IV_SPE | (uint)IV_SPA << 5 | (uint)IV_SPD << 10;
+    }
 }
diff --git a/PKHeX.Core/Legality/RNG/CXD/MethodCXD.cs b/PKHeX.Core/Legality/RNG/CXD/MethodCXD.cs
index 64ce9b899..868525f12 100644
--- a/PKHeX.Core/Legality/RNG/CXD/MethodCXD.cs
+++ b/PKHeX.Core/Legality/RNG/CXD/MethodCXD.cs
@@ -14,7 +14,7 @@ public static class MethodCXD
     public static bool SetFromIVs<T>(this T enc, G3PKM pk, EncounterCriteria criteria, PersonalInfo3 pi, bool noShiny = false) where T : IShadow3
     {
         var gr = pi.Gender;
-        (uint iv1, uint iv2) = GetCombinedIVs(criteria);
+        criteria.GetCombinedIVs(out var iv1, out var iv2);
         Span<uint> all = stackalloc uint[XDRNG.MaxCountSeedsIV];
         var count = XDRNG.GetSeedsIVs(all, iv1 << 16, iv2 << 16);
         var seeds = all[..count];
@@ -52,7 +52,7 @@ public static class MethodCXD
     public static bool SetFromIVsCXD(G3PKM pk, EncounterCriteria criteria, PersonalInfo3 pi, bool noShiny = true)
     {
         var gr = pi.Gender;
-        (uint iv1, uint iv2) = GetCombinedIVs(criteria);
+        criteria.GetCombinedIVs(out var iv1, out var iv2);
         Span<uint> all = stackalloc uint[XDRNG.MaxCountSeedsIV];
         var count = XDRNG.GetSeedsIVs(all, iv1 << 16, iv2 << 16);
         var seeds = all[..count];
@@ -174,13 +174,6 @@ private static uint GetPIDStarterMale(ref uint seed, uint id32)
 
     private static uint GetPIDRegular(uint a, uint b) => a << 16 | b;
 
-    private static (uint iv1, uint iv2) GetCombinedIVs(EncounterCriteria criteria)
-    {
-        uint iv1 = (uint)criteria.IV_HP | (uint)criteria.IV_ATK << 5 | (uint)criteria.IV_DEF << 10;
-        uint iv2 = (uint)criteria.IV_SPE | (uint)criteria.IV_SPA << 5 | (uint)criteria.IV_SPD << 10;
-        return (iv1, iv2);
-    }
-
     private static void SetIVs(G3PKM pk, uint iv1, uint iv2)
     {
         Span<int> ivs = stackalloc int[6];
diff --git a/PKHeX.Core/Legality/RNG/ClassicEra/Gen3/GenerateMethodH.cs b/PKHeX.Core/Legality/RNG/ClassicEra/Gen3/GenerateMethodH.cs
index 2693c518b..d77389523 100644
--- a/PKHeX.Core/Legality/RNG/ClassicEra/Gen3/GenerateMethodH.cs
+++ b/PKHeX.Core/Legality/RNG/ClassicEra/Gen3/GenerateMethodH.cs
@@ -95,7 +95,7 @@ public static bool SetFromIVs<T>(this T enc, PK3 pk, EncounterCriteria criteria)
         where T : IEncounterSlot3
     {
         var gr = pk.PersonalInfo.Gender;
-        (uint iv1, uint iv2) = GetCombinedIVs(criteria);
+        criteria.GetCombinedIVs(out var iv1, out var iv2);
         Span<uint> all = stackalloc uint[LCRNG.MaxCountSeedsIV];
         var count = LCRNGReversal.GetSeedsIVs(all, iv1 << 16, iv2 << 16);
         var seeds = all[..count];
@@ -163,7 +163,7 @@ public static bool SetFromIVs<T>(this T enc, PK3 pk, EncounterCriteria criteria)
     public static bool SetFromIVsUnown<T>(this T enc, PK3 pk, EncounterCriteria criteria)
         where T : IEncounterSlot3
     {
-        (uint iv1, uint iv2) = GetCombinedIVs(criteria);
+        criteria.GetCombinedIVs(out var iv1, out var iv2);
         Span<uint> all = stackalloc uint[LCRNG.MaxCountSeedsIV];
         var count = LCRNGReversal.GetSeedsIVs(all, iv1 << 16, iv2 << 16);
         var seeds = all[..count];
@@ -235,11 +235,4 @@ private static void SetPIDIVSequential(PK3 pk, uint pid, uint rand)
         pk.IV32 = ((iv2 & 0x7FFF) << 15) | (iv1 & 0x7FFF);
         pk.RefreshAbility((int)(pid & 1));
     }
-
-    private static (uint iv1, uint iv2) GetCombinedIVs(EncounterCriteria criteria)
-    {
-        uint iv1 = (uint)criteria.IV_HP | (uint)criteria.IV_ATK << 5 | (uint)criteria.IV_DEF << 10;
-        uint iv2 = (uint)criteria.IV_SPE | (uint)criteria.IV_SPA << 5 | (uint)criteria.IV_SPD << 10;
-        return (iv1, iv2);
-    }
 }
diff --git a/PKHeX.Core/Legality/RNG/ClassicEra/Gen3/MethodH.cs b/PKHeX.Core/Legality/RNG/ClassicEra/Gen3/MethodH.cs
index fb2e48ad6..eb54e5e4e 100644
--- a/PKHeX.Core/Legality/RNG/ClassicEra/Gen3/MethodH.cs
+++ b/PKHeX.Core/Legality/RNG/ClassicEra/Gen3/MethodH.cs
@@ -564,10 +564,11 @@ private static bool IsOriginalLevelValid(byte min, byte max, byte format, uint l
         return LevelRangeExtensions.IsLevelWithinRange((int)level, min, max);
     }
 
-    private static uint GetExpectedLevel(ILevelRange enc, uint u16LevelRand)
+    private static uint GetExpectedLevel<T>(T enc, uint u16LevelRand) where T : ILevelRange
     {
-        uint mod = 1u + enc.LevelMax - enc.LevelMin;
-        return (u16LevelRand % mod) + enc.LevelMin;
+        var min = enc.LevelMin;
+        uint mod = 1u + enc.LevelMax - min;
+        return (u16LevelRand % mod) + min;
     }
 
     private static bool IsRockSmashPossible(byte areaRate, ref uint seed)
diff --git a/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/GenerateMethodJ.cs b/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/GenerateMethodJ.cs
index 2ac010489..0ab0c9923 100644
--- a/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/GenerateMethodJ.cs
+++ b/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/GenerateMethodJ.cs
@@ -89,7 +89,7 @@ public static bool SetFromIVsJ<T>(this T enc, PK4 pk, PersonalInfo4 pi, Encounte
         where T : IEncounterSlot4
     {
         var gr = pi.Gender;
-        (uint iv1, uint iv2) = GetCombinedIVs(criteria);
+        criteria.GetCombinedIVs(out var iv1, out var iv2);
         Span<uint> all = stackalloc uint[LCRNG.MaxCountSeedsIV];
         var count = LCRNGReversal.GetSeedsIVs(all, iv1 << 16, iv2 << 16);
         var seeds = all[..count];
@@ -124,11 +124,4 @@ public static bool SetFromIVsJ<T>(this T enc, PK4 pk, PersonalInfo4 pi, Encounte
     }
 
     public static uint GetPIDRegular(uint a, uint b) => b << 16 | a;
-
-    private static (uint iv1, uint iv2) GetCombinedIVs(EncounterCriteria criteria)
-    {
-        uint iv1 = (uint)criteria.IV_HP | (uint)criteria.IV_ATK << 5 | (uint)criteria.IV_DEF << 10;
-        uint iv2 = (uint)criteria.IV_SPE | (uint)criteria.IV_SPA << 5 | (uint)criteria.IV_SPD << 10;
-        return (iv1, iv2);
-    }
 }
diff --git a/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/GenerateMethodK.cs b/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/GenerateMethodK.cs
index 4c87a8c4c..b25846318 100644
--- a/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/GenerateMethodK.cs
+++ b/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/GenerateMethodK.cs
@@ -88,7 +88,7 @@ public static bool SetFromIVsK<T>(this T enc, PK4 pk, PersonalInfo4 pi, Encounte
         where T : IEncounterSlot4
     {
         var gr = pi.Gender;
-        (uint iv1, uint iv2) = GetCombinedIVs(criteria);
+        criteria.GetCombinedIVs(out var iv1, out var iv2);
         Span<uint> all = stackalloc uint[LCRNG.MaxCountSeedsIV];
         var count = LCRNGReversal.GetSeedsIVs(all, iv1 << 16, iv2 << 16);
         var seeds = all[..count];
@@ -123,11 +123,4 @@ public static bool SetFromIVsK<T>(this T enc, PK4 pk, PersonalInfo4 pi, Encounte
     }
 
     public static uint GetPIDRegular(uint a, uint b) => b << 16 | a;
-
-    private static (uint iv1, uint iv2) GetCombinedIVs(EncounterCriteria criteria)
-    {
-        uint iv1 = (uint)criteria.IV_HP | (uint)criteria.IV_ATK << 5 | (uint)criteria.IV_DEF << 10;
-        uint iv2 = (uint)criteria.IV_SPE | (uint)criteria.IV_SPA << 5 | (uint)criteria.IV_SPD << 10;
-        return (iv1, iv2);
-    }
 }
diff --git a/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/MethodJ.cs b/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/MethodJ.cs
index 2644e30f2..a66384bb4 100644
--- a/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/MethodJ.cs
+++ b/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/MethodJ.cs
@@ -456,10 +456,11 @@ private static bool IsOriginalLevelValid(byte min, byte max, byte format, uint l
         return LevelRangeExtensions.IsLevelWithinRange((int)level, min, max);
     }
 
-    private static uint GetExpectedLevel(ILevelRange enc, uint u16LevelRand)
+    private static uint GetExpectedLevel<T>(T enc, uint u16LevelRand) where T : ILevelRange
     {
-        uint mod = 1u + enc.LevelMax - enc.LevelMin;
-        return (u16LevelRand % mod) + enc.LevelMin;
+        var min = enc.LevelMin;
+        uint mod = 1u + enc.LevelMax - min;
+        return (u16LevelRand % mod) + min;
     }
 
     /// <summary>
diff --git a/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/MethodK.cs b/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/MethodK.cs
index a85c7a2c4..8367e21f1 100644
--- a/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/MethodK.cs
+++ b/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/MethodK.cs
@@ -482,10 +482,11 @@ private static bool IsOriginalLevelValid(byte min, byte max, byte format, uint l
         return LevelRangeExtensions.IsLevelWithinRange((int)level, min, max);
     }
 
-    private static uint GetExpectedLevel(ILevelRange enc, uint u16LevelRand)
+    private static uint GetExpectedLevel<T>(T enc, uint u16LevelRand) where T : ILevelRange
     {
-        uint mod = 1u + enc.LevelMax - enc.LevelMin;
-        return (u16LevelRand % mod) + enc.LevelMin;
+        var min = enc.LevelMin;
+        uint mod = 1u + enc.LevelMax - min;
+        return (u16LevelRand % mod) + min;
     }
 
     private static bool IsBugContestPossibleDeadlock(uint areaRate, ref uint result)
diff --git a/PKHeX.WinForms/Subforms/SAV_Encounters.cs b/PKHeX.WinForms/Subforms/SAV_Encounters.cs
index ef365a362..01f40a093 100644
--- a/PKHeX.WinForms/Subforms/SAV_Encounters.cs
+++ b/PKHeX.WinForms/Subforms/SAV_Encounters.cs
@@ -187,7 +187,7 @@ private EncounterCriteria GetCriteria(ISpeciesForm enc, EncounterDatabaseSetting
         var set = new ShowdownSet(editor);
         var criteria = EncounterCriteria.GetCriteria(set, editor.PersonalInfo);
         if (!isInChain)
-            criteria = criteria with { Gender = default }; // Genderless tabs and a gendered enc -> let's play safe.
+            criteria = criteria with { Gender = Gender.Random }; // Genderless tabs and a gendered enc -> let's play safe.
         return criteria;
     }