As our show begins, Team Rocket is up to their old tricks again laying a trap for our hero (and heroine). They decide to dig a hole to catch Ash of guard and capture Pikachu. The only problem is that they covered the hole so well that they forgot where they put it. They find the hole...the hard way. Meanwhile, Ash finally finds his way out of the Viridian Forest and into Pewter City. Upon entering Pewter City, Ash meets a very mysterious man who calls himself Flint. After trying to sell Ash and Misty rocks as souvenirs, Flint takes Ash to the local Pokémon Center. Upon entering the Pokécenter, Ash is surprised to see Nurse Joy. Nurse Joy explains that the Nurse Joy in Viridian City is her little sister (confused?). Nurse Joy then points out a poster to Ash, changing his life forever. The poster promotes the Pokémon League Championships. Ash, wanting to become a Pokémon Master, decides that this is the way to go. The only problem is that he has to win badges from 8 gym trainers to be eligible for the championships. Flint shows up and taunts Ash for thinking he can defeat the Pewter City gym leader Brock. After an uneasy meal (and an expensive one at that), Ash decides to try his luck against Brock.
Upon entering the Pewter City gym, Ash meets up with Brock. Brock, sensing Ash's inexperience, informs him of the official tournament rules. Both he and Ash must choose 2 Pokémon with which to do battle. Ash starts with Pikachu and Brock chooses Onix. Needless to say, Pikachu is scared stiff by this giant Pokémon. Brock has Onix use Tackle on Pikachu, but Pikachu narrowly dodges him. However, Brock quickly has Onix follow up with his Bind attack. Ash has Pikachu use Thundershock, but to no effect (duh, an electric attack on a rock/ground Pokémon...come on Ash). Ash tries to call Pikachu back, but can't get around Onix who is still using Bind on Pikachu. Ash decides to surrender rather than have Pikachu seriously injured, losing the fight. On his way out of the gym, though, he runs into Flint who asks Ash to follow him. At Flint's house, Ash can't get over how good Brock was. Flint agrees, saying that Brock's talent could take him much further than local gym leader. Flint shows Ash why Brock can't move on to bigger things, and what he sees surprises him. Brock is taking care of 10 little brothers and sisters at home since his father left to become a Pokémon trainer and his mother passed away. Ash asks Flint to stop with the story, or else he won't be able to beat Brock. Flint admires Ash's persistence and tells Ash that there might be a way to super-charge Pikachu...
Flint takes Ash to a hydro-electric plant, telling Ash that if he hooks Pikachu up to it, there's a chance he could give Pikachu a power-boost. The only problem is the river's dry, leaving the plant un-powered. The only solution is to have Ash power it himself by running on the wheel which usually powers the plant. Misty shows up and asks Ash if he needs some help. Ash turns her offer down, telling her that he wants to earn the badge all by himself. All of the energy is overwhelming to Pikachu at first, but finally he reaches the point where he can control and re-channel his new power. Ash is now ready to challenge Brock a second time. Brock is cocky from the last fight and decides to start with Geodude. Ash sends out Pidgeotto who uses his Gust attack. The only problem is flying-type Pokémon are weak against rock-types (nice going Ash). Misty is silently cheering Ash on from the rafters, but she is soon crowded by Brock's brothers and sisters. Ash recalls Pidgeotto and sends out his new and improved Pikachu.
Pikachu takes care of Geodude with a powerful electric attack, shocking Brock and even Misty. Brock sends Onix out, once again scaring Pikachu. Pikachu unleashes another electric attack, but the attack is unfocused. It does heavy damage to the gym but barely harms Onix. Onix uses Bind on Pikachu again, but Pikachu uses his new attack Thunderbolt. The attack starts to work, but Pikachu can't sustain it while being binded by Onix. When it looks like Onix is about to faint Pikachu, however, Brock calls Onix off. He explains that he doesn't really want to hurt Pikachu and so asks Ash to surrender the match again. It looks like Ash is about to accept when all of the sudden, the gym sprinklers start up from a fire caused by Pikachu's earlier unfocused attack. The water severly weakens Onix and Ash uses this to his advantage. He has Pikachu attack Onix one more time with an electric attack. The electric attack is very effective thanks to the water, and Onix faints. Right when Ash is ready to finish Onix off, his conscience gets the better of him (as well as Brock's brothers and sisters). He calls Pikachu off, remembering when Brock called Onix off, and he leaves the gym. Brock tries to stop him, but Ash tells him that it was just a fluke that the sprinklers went off, and that he wanted to win fair and square.
On his way out of Pewter City, Ash is stopped by Brock who gives Ash a Boulder Badge. Brock explains that Ash earned it by being so kind to Pokémon. Brock doesn't really want to be a Pokémon trainer, he wants to be a Pokémon breeder. The only thing holding him back are his duties at home. Suddenly, Flint arrives telling Brock to go follow his dreams (he's actually Brock's dad!). Flint didn't come back to his family because he failed as a Pokémon trainer and couldn't face them. Brock has a few things to tell his father after so many years (all of them quite entertaining). In the end, Brock decides to follow Ash on his journey. Misty...well she won't leave until she gets a new bike, so Ash takes off with Brock to try and lose Misty. And what of Team Rocket? Well they finally get out of the hole, only to be ran over by Ash and company...and fall back into the hole. Oh well, better luck next time Team Rocket...