Instructions
Play through the game's storyline until you reach the Safari Zone area of Fuschia City. Talk to the Game Warden in the Safari Zone and he will ask you to complete two missions before you can start customizing the Safari Zone.
Capture a Geodude and a Sandshrew to show to the Game Warden. Geodude is commonly found in multiple areas of the game while Sandshrew is found in the desert region of the Safari Zone. Battle these Pokemon using your best Pokemon and special attacks to reduce their health points low enough so that you can capture them with a Pokeball.
Talk to the Game Warden and show him your Geodude to unlock the ability to move around the different zones of the Safari Zone. To move a zone, bring up the Safari Zone menu and use the DS Stylus to rearrange the zones. Show him your Sandshrew to unlock the ability to add objects to the different zones.
Talk to the Game Warden each day to receive new objects to place in the Safari Zone. If you do not want to wait, set the clock of your Nintendo DS forward to the next day to receive the next set of items. Press the "A" button at any point in the Safari Zone to place an object.
Place 25 Peak Objects in the desert region of the Safari Zone to attract Trapinch. Peak objects include Small Rock, Big Rock and Mossy Rock.
Walk on the grassy areas of the desert region of the Safari Zone to encounter a wild Trapinch once you have placed the Peak Objects. Battle the Trapinch using your best Pokemon and strategies to lower its health points enough to capture it using a Safari Ball.