Disallow move suggestions for formats < 6

Flip requirement from gennumber to format (since the moves are learnable
on said format)

PKHeX/Legality/Analysis.cs

@@ -210,7 +210,7 @@ public int[] getSuggestedRelearn()
         }
         public int[] getSuggestedMoves(bool tm, bool tutor)
         {
-            if (pkm.GenNumber < 6)
+            if (pkm.Format < 6)
                 return null;
             return Legal.getValidMoves(pkm, Tutor: tutor, Machine: tm).Skip(1).ToArray(); // skip move 0
         }

PKHeX/MainWindow/Main.cs

@@ -1784,6 +1784,9 @@ private void clickMoves(object sender, EventArgs e)
             {
                 bool random = ModifierKeys == Keys.Control;
                 int[] m = Legality.getSuggestedMoves(tm: random, tutor: random);
+                if (m == null)
+                { Util.Alert("Suggestions are not enabled for this PKM format."); return; }
+
                 if (random)
                     Util.Shuffle(m);
                 if (m.Length > 4)