Ritchie first appeared in A Friend In Deed and quickly befriended his fellow Pokémon League competitor, Ash Ketchum. This led to problems in the next episode, Friend or Foe Alike, since the two were matched up to battle against each other. Ritchie won the match, since at the very end Ash's Charizard refused to fight Sparky and took a nap on the battlefield instead. Even though he lost in the next match to Assunta, he made it to the Top 8 position in the league.

Ritchie showed up again in the anime when Ash and co. visited the Whirl Islands, starting in The Mystery is History. He was searching for a mysterious Pokémon that can be found there, which turned out to be a Lugia.

He also appeared in three Pokémon Chronicles episodes; Oaknapped, Celebi and Joy and The Search for the Legend.

[credit to bulbapedia]