The Universal Doomsday Machine (or UDM for short) is the final boss of Nicktoons Unite!. The heroes have found their way to the underground lair of Professor Calamitous and encounter him, along with Vlad Plasmius, Plankton and Denzel Crocker in the device. The UDM is powered with Ghost Energy, Jellyfish Jelly and Fairy Magic each coming from another dimension. The device itself was build by Calamitous. When the villains are defeated the UDM is still active, but luckily SpongeBob pulls out the plugs, and because Calamitous didn't have a backup power suply his plan failed.
The UDM will spin around the whole time and then stop at a random villain. Each villain will preform an attack. Vlad lets purple ghost balls rain down from the sky, Crocker shoots light orbs in the shape of stars, Plankton shoots bubbles everywhere and Calamitous sends out a laser that, when connected to each player will deal massive damage. After a few spins enemies will be summoned.
You have to press the buttons in that way that you can cross the bridges. When a leaver is pulled of a certain villain their protection orb will disappear and they are vurnable for attacks. When Vlad, Crocker and Plankton all have been defeated you can defeat Calamitous, not earlier.