Instructions
Obtain the National Pokedex by encountering every Pokemon in the Johto region and then talking to Professor Oak.
Travel to the Safari Zone, west of Cianwood.
Talk to Baoba inside the entrance to the Safari Zone to receive your first challenge.
Catch a Geodude in the Peak area of the Safari Zone; it is the first area encountered when you enter the Safari Zone.
Wait three hours for Baoba to call you and ask you to customize the Safari Zone. Use the "Area Customize" tool to add the Desert Zone, and catch a Sandshrew in it.
Place the forest objects, which are stumps and branches, that Baoba gives you in the Swamp Zone. The location of the Swamp Zone is random, but you can use the "Area Customize" tool to choose where it goes. Over time, Baoba will give you up to 30 items to place in the zone.
Place 15 forest items in the Swamp Zone. Simply press "A" to place an object in the Safari Zone.
Walk in the grass of the Swamp Zone until Chimecho appears.