Handle level20 transferred feebas edge case

Closes #2394 thanks @iiippppk !

PKHeX.Core/Legality/Evolutions/EvolutionType.cs

@@ -52,5 +52,6 @@ namespace PKHeX.Core
     public static class EvolutionTypeExtensions
     {
         public static bool IsTrade(this EvolutionType t) => t == Trade || t == TradeHeldItem || t == TradeSpecies;
+        public static bool IsLevelUpRequired(this EvolutionType t) => t.ToString().StartsWith("LevelUp"); // don't use this
     }
 }

Tests/PKHeX.Core.Tests/Legality/LegalityData.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using FluentAssertions;
+using PKHeX.Core;
+using Xunit;
+
+namespace PKHeX.Tests.Legality
+{
+    public class LegalityData
+    {
+        [Fact]
+        public void EvolutionsOrdered() // feebas, see issue #2394
+        {
+            var trees = typeof(EvolutionTree).GetFields(BindingFlags.Static | BindingFlags.NonPublic);
+            foreach (var t in trees)
+            {
+                var gen = Convert.ToInt32(t.Name[7].ToString());
+                if (gen <= 4)
+                    continue;
+
+                var fTree = (EvolutionTree)t.GetValue(typeof(EvolutionTree));
+                var fEntries = typeof(EvolutionTree).GetFields(BindingFlags.NonPublic | BindingFlags.Instance).First(z => z.Name == "Entries");
+
+                var entries = (IReadOnlyList<EvolutionMethod[]>)fEntries.GetValue(fTree);
+                var feebas = entries[(int)Species.Feebas];
+
+                var t1 = (EvolutionType)feebas[0].Method;
+                var t2 = (EvolutionType)feebas[1].Method;
+
+                t1.IsLevelUpRequired().Should().BeFalse();
+                t2.IsLevelUpRequired().Should().BeTrue();
+            }
+        }
+    }
+}