Ash Ketchum, a 10-year-old boy from Pallet Town, is starting his Pokémon journey. However, on the day he's due to start, he accidentally sleeps in and has to start off with the worst Pokémon of the bunch, Pikachu.

It's not long, however, before Ash and Pikachu become good friends and start working together. Team Rocket, a trio of villians, start attacking injured Pokémon, and Misty, a girl not much older than Ash, helps him defeat them. She then joins him on his quest, mainly because she wants Ash to replace a bike of hers which he destroyed in an attempt to save Pikachu. Soon after, Ash catches his first Pokémon, Caterpie, which quickly evolves into Metapod, followed by its most advanced form, Butterfree.

In only a couple of weeks, Ash, using Pikachu, manages to defeat Brock, the first gym leader. He receives his badge, and Brock also decides to join Ash's group.

Ash later battles Misty, of all people, for his second badge. But, since Misty was a part of Ash's group, Pikachu refused to battle her Pokémon and the battle was declared a tie. Ash saved the gym from Team Rocket, however, and because of that received the badge.

Ash, Pikachu, and his other Pokémon continued battling for badges, and Ash eventually won 6 of the 8 badges he needed to compete in the ultimate Pokémon contest, the Pokémon League.

Ash receives his fourth Orange League badge, and is ready to compete in the league itself.

Ash indeed wins the Orange League, and receives a winner's trophy. Ash returns home to Pallet Town, where he is surprised to find Brock at his own house. Brock had returned from Professor Ivy's ("I don't wanna talk about it," he declares). Tracey decides to stay at Professor Oak's lab as an aide, and Brock announces that he'll again join Ash and Misty.

Ash had barely been in Pallet Town a few days before Professor Oak tells him that Gary, Ash's main rival, had already headed off on a new Pokémon journey. Gary had left to participate in the Johto League, which worked in a similar way to the Pokémon League--you had to get eight badges before you could participate.

The Johto League was held in the province of Johto, to the west of the areas where the Pokémon and Orange Leagues were held. The Johto province was filled with many Pokémon never discovered elsewhere, and, being the Pokémon trainer he was, Ash was enthusiastic to compete in the Johto League and capture the Pokémon exclusive to the area. He left soon after, along with Misty and Brock, and made a beeline for the province of Johto, and his next Pokémon journey!