Bonz has the upper hand, as his Zombie-Type monsters gain a 30% ATK and DEF bonus because of the Graveyard Field, and when they are destroyed, they just regenerate, and become even stronger from "Call of the Haunted". However, when Yugi and the gang arrive, Joey manages to figure out the Zombie's main weakness and that is their DEF is 0. Using "Shield & Sword" to switch their ATK and DEF values, Joey wins the Duel. Bandit Keith then locks the gang in, double crosses his three companions, and enters the Duelist Kingdom Finals after taking Zygor and Sid's five Star Chips by force.
Different qualities aren't limited only to wild pets—many rare World drops and special non-wild companions have had their stats boosted. For example, the world-drop dragon whelps (Azure Whelpling, Crimson Whelpling, Dark Whelpling, and Emerald Whelpling) are of [rare] quality. Check your Pet Journal to see the color-coded rarity of your non-wild pets.