Rewrite GiveBoxMonInitialMoveset_Fast (#4373)

* GiveBoxMonInitialMoveset_Fast rewrite

Fix duplicate move bug and change behavior to match GiveBoxMonInitialMoveset results

* Fixed issue with learnsets smaller than 4

src/pokemon.c

@@ -1689,25 +1689,43 @@ void GiveBoxMonInitialMoveset_Fast(struct BoxPokemon *boxMon) //Credit: Asparagu
     u16 species = GetBoxMonData(boxMon, MON_DATA_SPECIES, NULL);
     s32 level = GetLevelFromBoxMonExp(boxMon);
     s32 i;
-    u16 levelMoveCount = 0;
     u16 moves[MAX_MON_MOVES] = {0};
     u8 addedMoves = 0;
     const struct LevelUpMove *learnset = GetSpeciesLevelUpLearnset(species);
 
     for (i = 0; learnset[i].move != LEVEL_UP_MOVE_END; i++)
-        levelMoveCount++;
-
-    for (i = levelMoveCount; (i >= 0 && addedMoves < MAX_MON_MOVES); i--)
     {
+        s32 j;
+        bool32 alreadyKnown = FALSE;
+
         if (learnset[i].level > level)
-            continue;
+            break;
         if (learnset[i].level == 0)
             continue;
 
-        if (moves[addedMoves] != learnset[i].move)
-            moves[addedMoves++] = learnset[i].move;
+        for (j = 0; j < addedMoves + 1; j++)
+            if (moves[j] == learnset[i].move)
+            {
+                alreadyKnown = TRUE;
+                break;
+            }
+
+        if (!alreadyKnown)
+        {
+            if (addedMoves < MAX_MON_MOVES)
+            {
+                moves[addedMoves] = learnset[i].move;
+                addedMoves++;
+            }
+            else
+            {
+                for (j = 0; j < MAX_MON_MOVES - 1; j++)
+                    moves[j] = moves[j + 1];
+                moves[MAX_MON_MOVES - 1] = learnset[i].move;
+            }
+        }
     }
-    for (i = MAX_MON_MOVES - 1; i >= 0; i--)
+    for (i = 0; i < MAX_MON_MOVES; i++)
     {
         SetBoxMonData(boxMon, MON_DATA_MOVE1 + i, &moves[i]);
         SetBoxMonData(boxMon, MON_DATA_PP1 + i, &gMovesInfo[moves[i]].pp);