I would love him to get a solgaleo instead of Latias, It's Very more relevant, and he could mean something Just like the plot in episode 1 when Ash Saw a Ho-ho, that the sun was shining bright... It was a Solgaleo clarifing its way to Pokemon Master...ye ngl, the Legendaries such as Ho-Oh, Mewtwo, or really any of the “deity” level Legendaries such as the Creation and Tao Trio can be crossed off.
But specifically Solgaleo and Lunala along with the Legendaries on the “lower end” such as the Eon Duo, Bird Trio, and Beast Trio?
They’re absolutely fair game.
Something that makes sense to be Ash's unique legendary.
Another thing is that Solgaleo it's one of tree main legendary from region he became known as the Champion.
I really can't understand why Latias.
Also @jinnrob told about Mewtwo and Ho-ho characters delying them to be caught by Ash.
One, Go caught a Suicune that has the job to purify water across the world, It doesn't make sense remain under a trainer, but he does both things with no problem.
Two, arguments like "makes no sense" don't fit a lot in Pokemon anime series, so giving him Mewtwo and Ho-ho for me wouldn't be surprise...