Dialga appeared along with Palkia in The Battle Finale of Legend! when the Team Galactic leader, Cyrus took control of them with the power of the Red Chain. Once they were being controlled, Cyrus commanded them to open a portal for him and create a new universe before him. Once the portal is created, Ash and his friends along with the freed Lake Guardians frees them from the red chain. Cyrus, who turned against his followers, stepped into the portal and disappeared as it closes. Dialga and Palkia destroyed it with their signature moves and everything around the Spear Pillar and Mt. Coronet begins to fall apart. With the combined powers of the Lake Guardians, Ash and his friends managed to calm down both Dialga and Palkia and save the Sinnoh region from destruction. Soon after that, the Lake Guardians sends Dialga and Palkia back to their respective dimensions where they can live in peace once more.