Instructions
Play the game until you reach the Safari Zone. Speak to Baoba at the entrance and agree to take part in the aptitude test. Enter the zone and capture a Geodude as the first part of the test.
Wait for Baoba to call your character again for the second part of the test. Read the instructions for using the Area Customizer, and then capture a Sandshrew in the zone. You can now change the areas in the Safari Zone, but you cannot yet place objects.
Continue playing the game until you receive the National Dex. You will receive it from Professor Oak after defeating the Elite Four. Wait for Baoba to call to inform you that the Object Arrangement feature is now available at the Safari Zone.
Return to the Safari Zone and stand in front of the machine that is located to the right of the entrance area. Press the "A" button to activate it, and select the area in the zone that you want to change.
Enter the zone and then walk to the area where you want to place your objects. Make sure there is an open space in front of your character, and then press the "A" button to open your menu.
Select "OK" when prompted if you want to place an object, and then select the object that you want to place. The object's name is shown on the bottom screen, while its picture and description are shown on the top screen. Highlight the object that you want to place and then press the "A" button to place it.
Stand in front of an object in the Safari Zone and press the "A" button if you want to remove it and place it somewhere else.