Win the Ultimate Battle Tournament, and defeat Marduk in the final
battle. Then, go to the Park, and challenge any of the following
characters to unlock their Guardian Bakugan at the Bakugan Store. Defeat
them a second time to unlock the evolved form of their Guardian Bakugan.
Note: You must first purchase the Guardian Bakugan before you can
unlock its evolved form.

      Choji: Aquos Preyas; Aquos Preyas II Angelo/Diablo
      Dan: Pyrus Dragonoid; Pyrus Delta Dragonoid II
      Julie: Subterra Gorem; Subterra Hammer Gorem
      Marduk: Darkus Vladitor; Darkus Battle Axe Vladitor
      Masquerade: Darkus Hydranoid; Darkus Blade Hydranoid
      Runo: Haos Tigrerra; Haos Blade Tigrerra
      Shun: Ventus Skyress; Ventus Storm Skyress