diff --git a/PKHeX.Core/Saves/Substructures/Gen8/BS/BattleTowerWork8b.cs b/PKHeX.Core/Saves/Substructures/Gen8/BS/BattleTowerWork8b.cs
index 8e28430f2..3088b824a 100644
--- a/PKHeX.Core/Saves/Substructures/Gen8/BS/BattleTowerWork8b.cs
+++ b/PKHeX.Core/Saves/Substructures/Gen8/BS/BattleTowerWork8b.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.ComponentModel;
 
 namespace PKHeX.Core
@@ -6,10 +7,13 @@ namespace PKHeX.Core
     /// <summary>
     /// Stores progress within the Battle Tower for the four battle modes.
     /// </summary>
-    /// <remarks>size: ???</remarks>
+    /// <remarks>size: 0x1B8</remarks>
     [TypeConverter(typeof(ExpandableObjectConverter))]
     public sealed class BattleTowerWork8b : SaveBlock
     {
+        private const int OFS_ClassData = 20;
+        private const int COUNT_CLASSDATA = 4;
+
         public BattleTowerWork8b(SAV8BS sav, int offset) : base(sav) => Offset = offset;
 
         // Structure:
@@ -18,13 +22,80 @@ public sealed class BattleTowerWork8b : SaveBlock
         // int old_playmode;
         // uint btl_point;
         // uint day_challeng_cnt;
-        // BTLTOWER_CLASSDATA[] class_data; // 0x18
+        // BTLTOWER_CLASSDATA[4] class_data;
         // uint challenge_cnt;
         public int MasterRankMax { get => BitConverter.ToInt32(Data, Offset + 0x0); set => BitConverter.GetBytes(value).CopyTo(Data, Offset + 0x0); } // max_master_rank
         public int PlayMode      { get => BitConverter.ToInt32(Data, Offset + 0x4); set => BitConverter.GetBytes(value).CopyTo(Data, Offset + 0x4); }// play_mode
         public int PlayModeOld   { get => BitConverter.ToInt32(Data, Offset + 0x8); set => BitConverter.GetBytes(value).CopyTo(Data, Offset + 0x8); } // old_playmode
         public uint BP           { get => BitConverter.ToUInt32(Data, Offset + 0xC); set => BitConverter.GetBytes(value).CopyTo(Data, Offset + 0xC); } // btl_point
 
-        // class_data appears to be an array of 4, sized 0x68 each. There's 2 fields at the end instead of 2, dunno.
+        public uint ChallengeCount { get => BitConverter.ToUInt32(Data, Offset + 0x1B4); set => BitConverter.GetBytes(value).CopyTo(Data, Offset + 0x1B4); } // challenge_cnt
+
+        public BattleTowerClassData8b[] Records
+        {
+            get => GetRecords();
+            set => SetRecords(value);
+        }
+
+        private BattleTowerClassData8b[] GetRecords()
+        {
+            var result = new BattleTowerClassData8b[COUNT_CLASSDATA];
+            for (int i = 0; i < result.Length; i++)
+                result[i] = new BattleTowerClassData8b(Data, Offset + OFS_ClassData + (i * BattleTowerClassData8b.SIZE));
+            return result;
+        }
+
+        private static void SetRecords(IReadOnlyList<BattleTowerClassData8b> value)
+        {
+            if (value.Count != COUNT_CLASSDATA)
+                throw new ArgumentOutOfRangeException(nameof(value.Count));
+            // data is already hard-referencing the original byte array. This is mostly a hack for Property Grid displays.
+        }
+    }
+
+
+    [TypeConverter(typeof(ExpandableObjectConverter))]
+    public sealed class BattleTowerClassData8b
+    {
+        public const int SIZE = 0x68;
+
+        private readonly int Offset;
+        private readonly byte[] Data;
+
+        public BattleTowerClassData8b(byte[] data, int offset)
+        {
+            Data = data;
+            Offset = offset;
+        }
+
+        public override string ToString() => $"Rank: {Rank}, Streak: {RenshouCount} (Max {RenshouCountOld}), Wins: {TotalWins}|{TotalWinsLoop}|{TotalWinsLose}";
+
+        public byte Cleared
+        {
+            get => Data[Offset + 0x00];
+            set => Data[Offset]= value;
+        }
+        public bool Suspended
+        {
+            get => BitConverter.ToInt32(Data, Offset + 0x04) == 1;
+            set => BitConverter.GetBytes(value ? 1u : 0u).CopyTo(Data, Offset + 0x04);
+        }
+        public ulong BattlePlaySeed  { get => BitConverter.ToUInt64(Data, Offset + 0x08); set => BitConverter.GetBytes(value).CopyTo(Data, Offset + 0x08); }
+        public uint Rank             { get => BitConverter.ToUInt32(Data, Offset + 0x10); set => BitConverter.GetBytes(value).CopyTo(Data, Offset + 0x10); }
+        public uint RankDownLose     { get => BitConverter.ToUInt32(Data, Offset + 0x14); set => BitConverter.GetBytes(value).CopyTo(Data, Offset + 0x14); }
+
+        public ulong TrainerSeed1 { get => BitConverter.ToUInt64(Data, Offset + 0x1C); set => BitConverter.GetBytes(value).CopyTo(Data, Offset + 0x1C); }
+        public ulong TrainerSeed2 { get => BitConverter.ToUInt64(Data, Offset + 0x24); set => BitConverter.GetBytes(value).CopyTo(Data, Offset + 0x24); }
+        public ulong TrainerSeed3 { get => BitConverter.ToUInt64(Data, Offset + 0x2C); set => BitConverter.GetBytes(value).CopyTo(Data, Offset + 0x2C); }
+        public ulong TrainerSeed4 { get => BitConverter.ToUInt64(Data, Offset + 0x34); set => BitConverter.GetBytes(value).CopyTo(Data, Offset + 0x34); }
+        public ulong TrainerSeed5 { get => BitConverter.ToUInt64(Data, Offset + 0x3C); set => BitConverter.GetBytes(value).CopyTo(Data, Offset + 0x3C); }
+        public ulong TrainerSeed6 { get => BitConverter.ToUInt64(Data, Offset + 0x44); set => BitConverter.GetBytes(value).CopyTo(Data, Offset + 0x44); }
+        public ulong TrainerSeed7 { get => BitConverter.ToUInt64(Data, Offset + 0x4C); set => BitConverter.GetBytes(value).CopyTo(Data, Offset + 0x4C); }
+
+        public uint TotalWins        { get => BitConverter.ToUInt32(Data, Offset + 0x54); set => BitConverter.GetBytes(value).CopyTo(Data, Offset + 0x54); }
+        public uint TotalWinsLoop    { get => BitConverter.ToUInt32(Data, Offset + 0x58); set => BitConverter.GetBytes(value).CopyTo(Data, Offset + 0x58); }
+        public uint TotalWinsLose    { get => BitConverter.ToUInt32(Data, Offset + 0x5C); set => BitConverter.GetBytes(value).CopyTo(Data, Offset + 0x5C); }
+        public uint RenshouCountOld  { get => BitConverter.ToUInt32(Data, Offset + 0x60); set => BitConverter.GetBytes(value).CopyTo(Data, Offset + 0x60); }
+        public uint RenshouCount     { get => BitConverter.ToUInt32(Data, Offset + 0x64); set => BitConverter.GetBytes(value).CopyTo(Data, Offset + 0x64); }
     }
 }