(MAJOR SPOILERS!!!!!)
pokemon movie 12 Arceus: to the conquering of space-time
Ash and his friends arrive at the beautiful land of Michina. Little did they expect to find once again to be found in a conflict between Dialga, Palkia, and Giratina. They are saved by a young woman called Sheena, who can communicate with a Pokemon's heart, and explains the whole conflict was because of Arceus being close to awakening. She also told her ancestor Damos betrayed Arceus and stole the Jewel of Life, sending it into a rage and a slumber. Sheena plans to return the Jewel to Arceus.
After a small after-conflict, Arceus fully awakens and returns to Earth, using its signature move Judgment to destroy Michina. Arceus see the Jewel is fake when Sheena tried to return it. Dialga, and Giratina return to try to stop Arceus, allowing Dialga to transport everyone but Kevin back in time to alter the past. They are nearly killed when Arceus attacks Damos and them, but Sheena prays to Dialga to send them further back in time. Arceus is apparently defeating the trio in the present day.
Ash, Brock, Dawn, and Sheena are several hours before Damos' betrayal. They attacked by an army of soldiers and takes in everyone but Sheena, who manages to warn a man in a toga of what will happen and takes her for interrogation.
When Ash and his friends find Damos in their same space, they react very negatively at him, but Damos begins to explain what happened in the past. Arceus began to die after defending the Earth from annihilation from a meteor and losing its 16 plates; Damos helped find them and heal Arceus. In return, Arceus detached 5 of its plates to make The Jewel of Life to make Michina rich and fertile. Damos claims he has no intention of stealing the jewel. He also claims the man in the toga is called Gishin. Brock remembered that Gishin was present when Damos was supposed to give back the plate in the first time Dialga sent them to by mistake, and theorizes he may be the mastermind on this.
Hosting a dining for Sheena, he is explained to by her Damos' true intent, and he agrees to help to stop him. He show an empty staff, which he secretly removed the jewel from, to Sheena, and goes to the temple with her. In the jail cell, a Notched-Ear Pichu befriended by Damos gives him the cell keys so they can escape.
At the temple, Arceus arrives and is told by Sheena that Damos will not be present. Gishin starts an attack, but Ash and his group arrives and Sheena comes to peace with her ancestor. Ash confronts Gishin with Monferno, but is overpowered by his heatran. He then fights Gishin physically, but fails. Gishing drops the jewel and is recovered by Ash.
Arceus is weaking by Gishin's attack and starts getting poured liquid metal on. Damos and Sheena become able to communicate with Gishin's Pokemon which are being controlled by armor. Ash's Pikachu destroys the armor. Arceus begins to die, causing a time paradox and Ash and his friends start to cease their existence. Ash's Pikachu fully vanishes, but before Ash fully disappears, he manages to give Arceus the Jewel back. The time paradox is canceled and everyone reappears and return to their proper time.
Expecting to find peace once again, they see Arceus has defeated Dialga, Palkia, and Giratina, and is preparing its final judgment. Ash cries out to it to remember that everything was fixed in the past. Arceus remembers and stops the attack, heals the dragon Pokemon, and restores Michina. The four legends bid their final farewell and return to their respective dimensions
sorry thats all i know