Unlike in Colosseum, XD has an area where you are capable of battling and capturing Wild Pokémon

There are three areas, Oasis, RockGround, Cave, that you can go to each with Wild Pokémon based on the area. They have to be activated by Duking in Pyrite Town first
What you need to do however in order to lure the wild Pokémon out is leave them food similar to how in Ruby, Sapphire & Emerald you leave PokéSnacks. When you're out and about you May get a symbol pop up on the screen similar to the one to the left. This means that a Pokémon has arrived at a PokéSpot. To check which open up your P*DA and have a look (such as in the picture to the right). The Spots glowing are the ones with Pokémon there. If it's glowing rapidly chances are a Munchlax has come and eaten your PokéSnacks. However usually its not so at your first opportunity and as soon as possible, go back to the PokéSpots and find & battle a Wild Pokémon
And thus the Wild Pokémon appear and you get a chance to capture them.

Below are the Pokémon obtainable in PokéSpot:

Picture	No.	Name	Level Caught	Location	Catch Rate	Gender
	#027	Sandshrew	Lv. 11-19	RockGround Spot	Common	50% Male ♂ 50% Female ♀
	#207	Gligar	Lv. 11-19	RockGround Spot	Uncommon	50% Male ♂ 50% Female ♀
	#328	Trapinch	Lv. 11-19	RockGround Spot	Rare	50% Male ♂ 50% Female ♀
	#187	Hoppip	Lv. 11-19	Oasis Spot	Common	50% Male ♂ 50% Female ♀
	#231	Phanpy	Lv. 11-19	Oasis Spot	Uncommon	50% Male ♂ 50% Female ♀
	#283	Surskit	Lv. 11-19	Oasis Spot	Rare	50% Male ♂ 50% Female ♀
	#041	Zubat	Lv. 11-19	Cave Spot	Common	50% Male ♂ 50% Female ♀
	#304	Aron	Lv. 11-19	Cave Spot	Uncommon	50% Male ♂ 50% Female ♀
	#194	Wooper	Lv. 11-19	Cave Spot	Rare	50% Male ♂ 50% Female ♀