Relationship beyond time and space

Ever wonder why Ash Ketchum is so dense, seemingly never age and overall still lack something that make him a Pokemon master? Well, in this story i got the answer for you!!!!
The plot take place during Ash's adventure in Alola. Everything is normal until Ash had a strange dream that appear to be one of his missing memory, after that a mysterious sinister force appear and claim to be a part of Ash's past appear and start to threaten Ash as well as his friend/family's life. What will our young Pokemon trainer do and will he be able to recover what seem to missing from himself?
DISCLAIMER: No I Don't Own Pokémon or any of the other shows (if i do Amourshipping would be all over the places and Ash would win the Kalos lueague )