After failing to win in the Kalos pokemon league almost all of Ash's friends and even his own mother betrayed him and when he went to Professor Oaks lab to get his Pokemon he found out that almost all of them betrayed him as well even the newly caught friends from Kalos. Before Ash has a chance to leave though the traitors decided that they would end Ash so they ordered every Pokémon to attack Ash. Meanwhile in the Hall of Origin Arceus called a meeting to see how Ash was doing and when they saw him in critical condition. Arceus has Hoopa bring them to the hall of origin to save them. However the damage had already been done. Ash was barely alive and seeing him like this made everyone upset, one more than the others. The only two loyal begged Arceus to revive Ash but he said he could only do it if he turned Ash into a Legendary Pokémon and Arceus decided to turn Ash into a Latios since he knew both Ash and Latias had feelings for each other