Instructions
Play the game as normal until you have access to the "Safari Zone," which is located left of "Cianwood City." You'll receive a phone call from "Baoba" the warden as soon as it becomes available.
Travel to the Safari Zone and agree to take the "Owner Aptitude Test" when Baoba asks you. The first part of the test involves catching a "Geodude" Pokemon. Pay Baoba the entrance fee and you'll receive 30 "Safari Balls."
Enter the zone and walk around in the tall grass until you encounter a "Geodude." Throw the Safari Ball at it for a capture and then return to Baoba.
Continue playing the game as normal until Baoba calls you and tells you that the second part of the test is available. Return to the Safari Zone and speak to Baoba again. You'll get instructions for using the "Area Customizer" feature and will be told to catch a "Sandshrew."
Stand in front of the "Area Customizer" that's located on the right-hand side of the Safari Zone entrance. Highlight any of the areas in the Zone and press the "A" button. Select "Desert" area and press "A" again. The area you have selected will be turned into a desert area that's perfect for catching a "Sandshrew."
Enter the Zone and go to the desert area that you created. Walk around in the tall grass until you encounter a Sandshrew and then throw a Safari ball at it for a capture. Return to Baoba, who will inform you that you have passed the test and are now the owner of the zone.
Continue playing the game as normal until you've obtained the "National Dex," and Baoba will call you again. This time he will inform you about the "Object Arrangement" feature, which allows you to place objects in the park that will lure otherwise unobtainable Pokemon to it.
Return to the zone and use the "Area Customizer" to turn one of the zones into a "Swamp." Enter the zone and walk to the swamp area. Stand anywhere in the swamp area where there is nothing in front of your character and press the "A" button to open a menu.
Select "OK" when asked if you want to place an object. Put down nine "Forest" and 19 "Rocky" blocks. If you don't have enough of these blocks, keep playing the game until Baoba calls you and tells you that more blocks are available. Blocks that you placed also "upgrade" and count towards more blocks over time.
Walk through the tall grass in the swamp area that you created with all of the blocks to encounter Bagon. Advance the date on your DS with 110 days unless you want to really wait that long for Bagon to become available. Throw the Safari Balls at Bagon until you have captured it.
Exit the zone and place Bagon at the head of your party. Fight against wild Pokemon and defeat them to gain experience. Once Bagon reaches level, 30 it will evolve into a Shelgon.
Continue using the Shelgon in battles for it to gain experience and level up. Once Shelgon reaches level 50, it will evolve into a Salamence.