Pokemon: Rise of the Final Reckoning

Five years ago, he defeated Leon, the reigning champion, to claim the title. But his path has been anything but easy. Ash Ketchum has walked through fire-losing his mother in a devastating Team Rocket assault, then losing the two people who became his family afterward: Professor Kukui and Professor Burnet, who loved him like their own.
In the darkness that followed, only a few stood by him: the wise Professor Oak, his lifelong rival and closest friend Gary Oak, his loyal friends from Alola, and the light of his life-Kalos Queen Serena Yvonne.
Now, the stage is set for the ultimate challenge: The Grand Masters Tournament-where the world's top 100 trainers, including regional champions and elite masters, clash for the right to face the World Monarch and earn the title of World's Strongest Trainer.
Can Ash Ketchum-Champion of Alola and Kanto, Aura Master, descendant of both Arceus and Abyzrael, and the current World Monarch-conquer his past, rise above the trauma, and crush those who seek to plunge the Pokémon World into chaos?
The world watches. Destiny awaits.

A/N: In this story, Paldea does not exist. It will be from Gen 1 to Gen 8.