Spoiler warning! This article contains spoilers for the game.
Maladeux makes its appearance towards the end of the Vesryn storyline at the Circle of Power. Artemis/Loki attempts to summon Maladeux in an effort to rival Zeus/Odin and his Divaevus. During this time, the villain explains that Maladeux exists as Arceus's Dread Plate whereas Divaevus exists as Arceus's Divine Plate. Artemis/Loki then begins to summon the creature, only to be thwarted by Jake who uses Victini/Jirachi's power to call forth the creature instead and then captures it using a Master Ball.
After using Maladeux's Tesseract attack to send Artemis/Loki into the past, Jake then challenges the player to a battle using his newly acquired "Swagadeux". Maladeux does not make an appearance again after this battle ends.