Richie is a friend who Ash met in the Pokémon League. He appeared in the series and in the manga. Like Ash his goal is to become a Pokémon Master. In the series his Pokémon are a Pikachu called Sparky, a Charmander called Zippo and a Butterfree named Happy. In the manga he ownes a Pikachu named Chuchino, a Butterfree, also called Happy and instead of Zippo he ownes a Charizard called Charley. In both the TV-Series and the manga he beats Ash in the League, but in the manga Ash would have probably won if he hadn't recalled his out of control Charizard that was trying to kill Richie's Charley. In the series Richie lost in the next round, in the manga you can't tell.
Richie is probably the same age as Ash (10), and they both own similar Pokémon.
In the TV-Series Richie and Ash bust Team Rocket's plan of stealing a load of
Pokémon, and then became best friends. After Richie beat Ash they promised
each other that they would both try very hard to become Pokémon Masters.
Richie only appeared in three episodes, but he's still my favourite character. I don't
suppose he'll turn up again, like all the other trainers Ash met, but he does appear
in the Orange League TV-Series intro.
Maybe he and Ash will meet again, I hope so.