diff --git a/PKHeX.Core/Legality/LearnSource/LearnEnvironment.cs b/PKHeX.Core/Legality/LearnSource/LearnEnvironment.cs
index ca18a8a3b..0ccc41b88 100644
--- a/PKHeX.Core/Legality/LearnSource/LearnEnvironment.cs
+++ b/PKHeX.Core/Legality/LearnSource/LearnEnvironment.cs
@@ -6,8 +6,14 @@ namespace PKHeX.Core;
 /// <summary>
 /// Indicates the group of game(s) that the move was learned in.
 /// </summary>
+/// <remarks>
+/// Each unique set of learnsets has a unique <see cref="LearnEnvironment"/> value.
+/// </remarks>
 public enum LearnEnvironment : byte
 {
+    /// <summary>
+    /// Sentinel value indicating no environment specified/initial environment.
+    /// </summary>
     None,
 
     /* Gen1 */ RB, YW,
@@ -27,7 +33,14 @@ public enum LearnEnvironment : byte
 /// </summary>
 public static class LearnEnvironmentExtensions
 {
+    /// <summary>
+    /// Indicates whether the <see cref="LearnEnvironment"/> is specified (not <see cref="None"/>), and thus worth indicating.
+    /// </summary>
     public static bool IsSpecified(this LearnEnvironment value) => value is not None;
+
+    /// <summary>
+    /// Gets the generation number (1-n) for the given <see cref="LearnEnvironment"/>.
+    /// </summary>
     public static byte GetGeneration(this LearnEnvironment value) => value switch
     {
         RB or YW => 1,
@@ -42,6 +55,9 @@ public static class LearnEnvironmentExtensions
         _ => 0,
     };
 
+    /// <summary>
+    /// Retrieves the evolution criteria for the given <see cref="LearnEnvironment"/> from the provided <see cref="EvolutionHistory"/>.
+    /// </summary>
     public static ReadOnlySpan<EvoCriteria> GetEvolutions(this LearnEnvironment value, EvolutionHistory history) => value switch
     {
         RB or YW => history.Gen1,
diff --git a/PKHeX.Core/Legality/LearnSource/MoveLearnInfo.cs b/PKHeX.Core/Legality/LearnSource/MoveLearnInfo.cs
index e4644ee7f..9a0abf1cb 100644
--- a/PKHeX.Core/Legality/LearnSource/MoveLearnInfo.cs
+++ b/PKHeX.Core/Legality/LearnSource/MoveLearnInfo.cs
@@ -13,12 +13,18 @@ namespace PKHeX.Core;
 /// <param name="Argument">Conditions in which the move was learned</param>
 public readonly record struct MoveLearnInfo(LearnMethod Method, LearnEnvironment Environment, byte Argument = 0)
 {
+    /// <inheritdoc cref="Summarize(StringBuilder, ReadOnlySpan{char})"/>
     public void Summarize(StringBuilder sb)
     {
         var localized = GetLocalizedMethod();
         Summarize(sb, localized);
     }
 
+    /// <summary>
+    /// Summarizes the move learn info into a human-readable format and appends it to the provided <see cref="StringBuilder"/>.
+    /// </summary>
+    /// <param name="sb">The <see cref="StringBuilder"/> to append the summary to.</param>
+    /// <param name="localizedMethod">The localized string representing the learning method.</param>
     private void Summarize(StringBuilder sb, ReadOnlySpan<char> localizedMethod)
     {
         if (Environment.IsSpecified())
diff --git a/PKHeX.Core/Legality/RNG/ClassicEra/ClassicEraRNG.cs b/PKHeX.Core/Legality/RNG/ClassicEra/ClassicEraRNG.cs
index b2cacf712..8776303da 100644
--- a/PKHeX.Core/Legality/RNG/ClassicEra/ClassicEraRNG.cs
+++ b/PKHeX.Core/Legality/RNG/ClassicEra/ClassicEraRNG.cs
@@ -1,5 +1,4 @@
 using System;
-using System.ComponentModel.DataAnnotations;
 
 namespace PKHeX.Core;
 
@@ -271,21 +270,3 @@ public static uint SeekInitialSeedForIVs(ReadOnlySpan<int> ivs, uint year, uint
         return best;
     }
 }
-
-/// <summary>
-/// Stores the components of an initial seed from Generation 4.
-/// </summary>
-public readonly record struct InitialSeedComponents4
-{
-    [Range(0, 99)] public required byte Year { get; init; }
-    [Range(1, 12)] public required byte Month { get; init; }
-    [Range(1, 31)] public required byte Day { get; init; }
-    [Range(0, 23)] public required byte Hour { get; init; }
-    [Range(0, 59)] public required byte Minute { get; init; }
-    [Range(0, 59)] public required byte Second { get; init; }
-
-    public required ushort Delay { get; init; } // essentially XXX-65535, but can overflow. Not that anyone waits the 30+ minutes to do that since other initial seeds are more efficient.
-
-    public uint ToSeed() => ClassicEraRNG.GetInitialSeed(Year, Month, Day, Hour, Minute, Second, Delay);
-    public bool IsInvalid() => Month == 0;
-}
diff --git a/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/CuteCharm4.cs b/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/CuteCharm4.cs
index 0f7680494..501989999 100644
--- a/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/CuteCharm4.cs
+++ b/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/CuteCharm4.cs
@@ -18,11 +18,16 @@ public static uint GetPIDMale(byte genderRatio, uint nature)
     {
         // pid >= ratio is male
         // get the lowest PID that will be male for Hardy (0)
-        var basePID = NatureCount * ((genderRatio / NatureCount) + 1);
+        var basePID = GetBufferedBasePID(genderRatio);
         // add the desired nature to the base PID
         return basePID + nature;
     }
 
+    /// <summary>
+    /// Gets the starting PID for a male gender by rounding up to the next multiple of <see cref="NatureCount"/> (25).
+    /// </summary>
+    private static uint GetBufferedBasePID(byte genderRatio) => NatureCount * ((genderRatio / NatureCount) + 1);
+
     /// <summary>
     /// Gets the PID of a Female wild encounter when the player leads a Male Pokémon with Cute Charm.
     /// </summary>
@@ -39,6 +44,15 @@ private static byte GetGenderRatio(ushort species)
             : EntityGender.GetGenderRatio(species); // fallback (don't bother trying to devolve to Gen1-4 encounter species)
     }
 
+    /// <summary>
+    /// Checks if the PID is within the range created by the buffered PID algorithm.
+    /// </summary>
+    /// <param name="pid">Obtained PID</param>
+    /// <returns>True if the PID is within the Azurill male range.</returns>
+    /// <remarks>
+    /// The game starts with a PID of 200, and then adds nature (0-24) to it, resulting in a range of 200-224.
+    /// 200 is via <see cref="GetBufferedBasePID"/> with the 3F:1M gender ratio of Azurill (191).
+    /// </remarks>
     private static bool IsAzurillMale(uint pid) => pid is >= 0xC8 and <= 0xE0;
 
     /// <summary>
diff --git a/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/InitialSeedComponents4.cs b/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/InitialSeedComponents4.cs
new file mode 100644
index 000000000..fdd2a757b
--- /dev/null
+++ b/PKHeX.Core/Legality/RNG/ClassicEra/Gen4/InitialSeedComponents4.cs
@@ -0,0 +1,22 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace PKHeX.Core
+{
+    /// <summary>
+    /// Stores the components of an initial seed from Generation 4.
+    /// </summary>
+    public readonly record struct InitialSeedComponents4
+    {
+        [Range(0, 99)] public required byte Year { get; init; }
+        [Range(1, 12)] public required byte Month { get; init; }
+        [Range(1, 31)] public required byte Day { get; init; }
+        [Range(0, 23)] public required byte Hour { get; init; }
+        [Range(0, 59)] public required byte Minute { get; init; }
+        [Range(0, 59)] public required byte Second { get; init; }
+
+        public required ushort Delay { get; init; } // essentially XXX-65535, but can overflow. Not that anyone waits the 30+ minutes to do that since other initial seeds are more efficient.
+
+        public uint ToSeed() => ClassicEraRNG.GetInitialSeed(Year, Month, Day, Hour, Minute, Second, Delay);
+        public bool IsInvalid() => Month == 0;
+    }
+}
diff --git a/PKHeX.Core/Legality/Verifiers/GenderVerifier.cs b/PKHeX.Core/Legality/Verifiers/GenderVerifier.cs
index 4296bcb52..9241b82fb 100644
--- a/PKHeX.Core/Legality/Verifiers/GenderVerifier.cs
+++ b/PKHeX.Core/Legality/Verifiers/GenderVerifier.cs
@@ -12,8 +12,9 @@ public sealed class GenderVerifier : Verifier
     public override void Verify(LegalityAnalysis data)
     {
         var pk = data.Entity;
-        var pi = pk.PersonalInfo;
-        if (pi.Genderless != (pk.Gender == 2))
+        var pi = data.PersonalInfo;
+        var gender = pk.Gender;
+        if (pi.Genderless != (gender == 2))
         {
             // D/P/Pt & HG/SS Shedinja glitch -- only generation 4 spawns
             bool ignore = pk is { Format: 4, Species: (int)Species.Shedinja } && pk.MetLevel != pk.CurrentLevel;
@@ -36,7 +37,7 @@ public override void Verify(LegalityAnalysis data)
         }
 
         // Check fixed gender cases
-        if ((pi.OnlyFemale && pk.Gender != 1) || (pi.OnlyMale && pk.Gender != 0))
+        if ((pi.OnlyFemale && gender != 1) || (pi.OnlyMale && gender != 0))
             data.AddLine(GetInvalid(LGenderInvalidNone));
     }
 
@@ -65,22 +66,22 @@ private static bool IsValidGenderPID(LegalityAnalysis data)
         return true;
     }
 
-    private static bool IsValidFixedGenderFromBiGender(PKM pk, ushort original)
+    private static bool IsValidFixedGenderFromBiGender(PKM pk, ushort originalSpecies)
     {
         var current = pk.Gender;
         if (current == 2) // shedinja, genderless
             return true;
-        var gender = EntityGender.GetFromPID(original, pk.EncryptionConstant);
+        var gender = EntityGender.GetFromPID(originalSpecies, pk.EncryptionConstant);
         return gender == current;
     }
 
     private static bool IsValidGenderMismatch(PKM pk) => pk.Species switch
     {
         // Shedinja evolution gender glitch, should match original Gender
-        (int) Species.Shedinja when pk.Format == 4 => pk.Gender == EntityGender.GetFromPIDAndRatio(pk.EncryptionConstant, 0x7F), // 50M-50F
+        (int) Species.Shedinja when pk.Format == 4 => pk.Gender == EntityGender.GetFromPIDAndRatio(pk.EncryptionConstant, EntityGender.HH), // 1:1
 
         // Evolved from Azurill after transferring to keep gender
-        (int) Species.Marill or (int) Species.Azumarill when pk.Format >= 6 => pk.Gender == 1 && (pk.EncryptionConstant & 0xFF) > 0x3F,
+        (int) Species.Marill or (int) Species.Azumarill when pk.Format >= 6 => pk.Gender == 1 && (pk.EncryptionConstant & 0xFF) > EntityGender.MM, // 3:1
 
         _ => false,
     };
diff --git a/PKHeX.Core/Legality/Verifiers/GroundTileVerifier.cs b/PKHeX.Core/Legality/Verifiers/GroundTileVerifier.cs
index 4221efdff..0461d54e1 100644
--- a/PKHeX.Core/Legality/Verifiers/GroundTileVerifier.cs
+++ b/PKHeX.Core/Legality/Verifiers/GroundTileVerifier.cs
@@ -11,6 +11,9 @@ public sealed class GroundTileVerifier : Verifier
 
     public override void Verify(LegalityAnalysis data)
     {
+        // Only specific encounters in Generation 4 set a GroundTile value.
+        // This value is retained after transferring to Gen5, but not beyond.
+        // Gen3 and Gen5 encounters should never have a Tile value.
         if (data.Entity is not IGroundTile e)
             return;
         var enc = data.EncounterMatch;
@@ -27,7 +30,12 @@ public override void Verify(LegalityAnalysis data)
     /// <returns>True if stored ground tile value is permitted.</returns>
     public static bool IsGroundTileValid(IEncounterTemplate enc, IGroundTile e)
     {
-        var type = enc is IGroundTypeTile t ? t.GroundTile : GroundTileAllowed.None;
-        return type.Contains(e.GroundTile);
+        if (enc is not IGroundTypeTile t)
+            return e.GroundTile is GroundTileType.None;
+
+        var allow = t.GroundTile;
+        if (allow is GroundTileAllowed.None)
+            return e.GroundTile is GroundTileType.None;
+        return allow.Contains(e.GroundTile);
     }
 }
diff --git a/PKHeX.Core/Legality/Verifiers/MiscVerifier.cs b/PKHeX.Core/Legality/Verifiers/MiscVerifier.cs
index 0f21f1bf3..898a6c336 100644
--- a/PKHeX.Core/Legality/Verifiers/MiscVerifier.cs
+++ b/PKHeX.Core/Legality/Verifiers/MiscVerifier.cs
@@ -21,26 +21,34 @@ public override void Verify(LegalityAnalysis data)
         {
             VerifyMiscEggCommon(data);
 
+            // No egg have contest stats from the encounter.
             if (pk is IContestStatsReadOnly s && s.HasContestStats())
                 data.AddLine(GetInvalid(LEggContest, Egg));
 
+            // Cannot transfer eggs across contexts (must be hatched).
+            var e = data.EncounterOriginal;
+            if (e.Context != pk.Context)
+                data.AddLine(GetInvalid(LTransferEggVersion, Egg));
+
             switch (pk)
             {
-                case SK2 or CK3 or XK3 or BK4 or RK4 or PA8: // Side Game: No Eggs
+                // Side Game: No Eggs
+                case SK2 or CK3 or XK3 or BK4 or RK4 when e.Context == pk.Context:
                     data.AddLine(GetInvalid(LTransferEggVersion, Egg));
                     break;
-                case PK5 pk5 when pk5.PokeStarFame != 0:
-                    data.AddLine(GetInvalid(LEggShinyPokeStar, Egg));
+
+                // All Eggs are Japanese and flagged specially for localized string
+                case PK3 when pk.Language != 1:
+                    data.AddLine(GetInvalid(string.Format(LOTLanguage, LanguageID.Japanese, (LanguageID)pk.Language), Egg));
                     break;
+
+                // Cannot obtain Shiny Leaf or Pokeathlon Stats as Egg
                 case PK4 pk4:
                     if (pk4.ShinyLeaf != 0)
                         data.AddLine(GetInvalid(LEggShinyLeaf, Egg));
                     if (pk4.PokeathlonStat != 0)
                         data.AddLine(GetInvalid(LEggPokeathlon, Egg));
                     break;
-                case PK3 when pk.Language != 1:  // All Eggs are Japanese and flagged specially for localized string
-                    data.AddLine(GetInvalid(string.Format(LOTLanguage, LanguageID.Japanese, (LanguageID)pk.Language), Egg));
-                    break;
             }
 
             if (pk is IHomeTrack { HasTracker: true })
@@ -59,8 +67,8 @@ public override void Verify(LegalityAnalysis data)
             case PK9 pk9: VerifyStats9(data, pk9); break;
         }
 
-        if (pk.Format >= 6)
-            VerifyFullness(data, pk);
+        if (pk is IFullnessEnjoyment fe) // 6-8
+            VerifyFullness(data, pk, fe);
 
         var enc = data.EncounterMatch;
         if (enc is IEncounterServerDate { IsDateRestricted: true } encounterDate)
@@ -209,6 +217,12 @@ private void VerifyIsMovesetAllowed(LegalityAnalysis data, SK2 sk2)
     private static void VerifyStats5(LegalityAnalysis data, PK5 pk5)
     {
         var enc = data.EncounterMatch;
+
+        // Cannot participate in Pokestar Studios as Egg
+        if (pk5.IsEgg && pk5.PokeStarFame != 0)
+            data.AddLine(GetInvalid(LEggShinyPokeStar, Egg));
+
+        // Ensure NSparkle is only present on N's encounters.
         if (enc is EncounterStatic5N)
         {
             if (!pk5.NSparkle)
@@ -351,7 +365,7 @@ private static bool IsObedienceLevelValid(PKM pk, byte current, int expectObey)
     private void VerifyMiscPokerus(LegalityAnalysis data)
     {
         var pk = data.Entity;
-        if (pk.Format == 1)
+        if (pk.Format == 1) // not stored in Gen1 format
             return;
 
         var strain = pk.PokerusStrain;
@@ -622,10 +636,8 @@ public void VerifyVersionEvolution(LegalityAnalysis data)
         }
     }
 
-    private static void VerifyFullness(LegalityAnalysis data, PKM pk)
+    private static void VerifyFullness(LegalityAnalysis data, PKM pk, IFullnessEnjoyment fe)
     {
-        if (pk is not IFullnessEnjoyment fe)
-            return;
         if (pk.IsEgg)
         {
             if (fe.Fullness != 0)