Here is a simple guide for finding the first 5 challengers for Defenders of Neopia, however, fighting them is up to you!!!
Enemy: The Pant Devil
Location: Anywhere (wait until he robs you, then fight him)
Tips: None (this is a basic fight for experienced pets)
Enemy: The Ghost Lupe
Location: 131 Soup Alley (Click, in this order: “Pet Central”, “NeoHome”, “Neighbourhood”, “Neopia Central”, “Soup Alley”, then enter 131 as the address and he should appear.
Enemy: Cave Chia
Location: Cave Paintings, page two (You may have to refresh it several times)
Tips: He doesn’t use anything to special, no Downsize Power Pluses or the such