Reordering a bit.

Project/scripts/boxes_spawn/boxes_spawn.gml

@@ -0,0 +1,55 @@
+///boxes_spawn()
+
+if (file_exists(working_directory+"/Logs/MissingSprites.log"))
+    file_delete(working_directory+"/Logs/MissingSprites.log");
+
+/// SPAWN SLOTS
+
+var pos_x = 0;
+var pos_y = 0;
+
+global.current = 1;
+
+var jump = true;
+var gen_current = 0;
+
+for (global.box_count=1; global.current<global.dex_len; global.box_count++)
+{
+    // Headers
+    with (instance_create(0, 0, obj_header))
+    {
+        global.box_header[global.box_count] = self;
+        number = global.box_count;
+        image_index = get_gen(global.dexdata[global.current, dex.dexno])-1;
+        show_debug_message("Spawned Box "+string(global.box_count)+" with PKMN #"+string(global.dexdata[global.current, dex.dexno])+" from Gen "+string(get_gen(global.dexdata[global.current, dex.dexno])))
+        image_speed = 0;
+        
+        if (check_genfirst(global.dexdata[global.current, dex.pokemon], false))
+            global.gen_header[gen_current++] = global.box_count;
+            
+        jump = false;
+    }
+    
+    
+    for (var i=0; i<5; i++) // Box Y
+        for (var j=0; j<6; j++) // Box X
+        {
+            if (global.current<global.dex_len && !jump)
+            {
+                while(!check_skip(global.current) /*|| global.savedata[global.current]*/)
+                    global.current++;
+                
+                if (!check_jump(j, i, global.current))
+                {
+                    if (check_galar(global.current, global.show_galar))
+                        make_slot(j, i, global.current);
+                        
+                    global.current++;
+                }
+                else
+                    jump = true;
+            }
+        }
+}
+
+global.gen_header[gen_current] = global.box_count-1; // Last header.

Project/scripts/boxes_spawn/boxes_spawn.yy

@@ -0,0 +1,8 @@
+{
+    "id": "0c8bde50-6fda-efe6-8809-de6b265ccbcc",
+    "modelName": "GMScript",
+    "mvc": "1.0",
+    "name": "boxes_spawn",
+    "IsCompatibility": false,
+    "IsDnD": false
+}