Alright, a quick premise, things up until Unova has been the same as Anime. However, after Unova, Ash went somewhere for about 2 years, and then went directly to Alola. 

In Alola, once again he started with only Pikachu, and most of the stuff happened, except he wasn't as dumb as in the anime and was a very good battler. He put up a way better fight against everyone he had lost to in anime, with the exception of the Island Kahunas, who he was able to defeat on the first try. 

And he does age, he was 13 by Unova, giving him about 9 months for Kanto league, 3 months for Orange islands, 5 for Johto, 5 for Hoenn, 3 for Battle frontiers, and 5 for Sinnoh, and 6 for Unova. In between Sinnoh and Unova, the power of us movie events happened, though it doesn't matter if you haven't seen it, just know that Ash is friends with a Zeraora.

Ash is also Queen Illene's cousin, who is the sister of Riley.

Also, Ash kept Kalos for after becoming a champion, since... you'll find out. :)