Ash is a super important character, and is mainly used for comedy. He is acted by Dane Kevin Cook, who is by far the best actor in the series. He has had a lasting rivalry with Gary Oak, and is best friends with Brock.
Ash is very important in the series, he goes out and has fun with the Mario Brothers. He also plays Pokémon with his best friend, Brock. the series wouldn't be the same without him.
Ash plays a huge role in the Movie, too. He does, though, play Pokémon with his friend, Brock, and his rival, Gary. He eventually goes on to catch all 493 Pokémon before Gary, though, in ACT II Part 5.