>>58154981Trying Something New by PredictionPrincessMieru
https://archiveofourown.org/series/4053655A really well crafted story that has Ash re-evaluate himself during the Kalos arc. He ends up going to Alto Mare and reuniting with Latias eventually. Keep in mind that this story isn't advertised as an altoshipping story, but it's worth a read for anyone who likes the ship due to the quality and fluff it has between the two. It does appear it could evolve into something more later on as well.
Guardian Angels by ArcyAnderson
https://archiveofourown.org/works/50838811/chapters/128432380This story aims to do a rewrite of the original movie itself, while also placing it at the end of Sinnoh after Ash lost to Tobias. The Latis are presented as having a much larger role in the inner workings of Alto Mare and are essentially established to be gods in this. Author does a good job mirroring the plot beats of the old film, while also establishing something entirely unique.
As a bonus if you want something good with Alto Mare Latias:
Pokemon Academy Life: Forever by Freud
This is a visual novel where you play as Red and enter an elite battle school to become an aspiring trainer. Latias fans should enjoy how often she shows up after she's introduced and she could be a potential romance option whenever Freud gets to implementing that system.
