Ash and his friends hike along the path, quickly feeling the onset of fatigue. Team Rocket follows them, also feeling tired. Ash wishes for more Badges, but Misty points out that he won't be able to win Badges just for beating Team Rocket only. Jessie suggests that they stop following Ash and his friends to find a new target, as James mentions how many Pokémon Ash's friends have compared to them. He especially mentions Ash's Charizard, being notably powerful. As they walk, Ash mentions that with Pikachu and Charizard on his side, he could beat any opponent, but his friends mention that he uses Charizard excessively, making it unfair for opponents. The group overhears a faint echo, so Brock decides to call out an echo. A woman calls over to them from atop a cliff. Brock is as usual attracted as she points out how the echoes allow a person to hear for miles. While she introduces herself as Liza, Brock looks up the Charicific Valley in his guidebook. Liza knows that Ash has a Charizard by the scent on him and about his win in Violet City, wanting to meet him and invite him to the Valley. Brock agrees, which gets Ash to go.
Liza calls out "Charla" as a female Charizard arrives with a balloon attached to her tail. Liza hops onto Charla as she invites Misty and Brock to ride in the balloon. There isn't enough room for Ash, but Liza suggests for him to fly on his Charizard. Charla takes off as Ash asks how to ride, which stuns Liza that he never flew on Charizard. Ash summons his Charizard and requests a ride. Charizard refuses at first, but Liza's taunt motivates Charizard to try. Ash and Pikachu hop on Charizard as it stomps and flies off, but it accidentally leaves Ash and Pikachu behind. After getting them back on, Charizard flies with them onboard, but unsteadily, flapping its wings furiously. Meanwhile, Misty compliments Liza's Charla for flying smoothly, but Liza can't hear her too well, so they talk through a phone system. Liza mentions that the Charizard in the valley are wild, but Charla is a special one. When she mentions that the wild Charizard never see humans and that she protects them from poachers, Misty thinks Liza is taking them to jail as poachers, but Liza points out that she knows they care for Pokémon. Ash and Charizard catch up as Charla speeds forward. Charizard bolts forward, but Charizard suddenly stalls, plunging down, barely skirting the bottom of a river. They avoid crashing into trees before plummeting into the abyss. Meanwhile, Team Rocket slides down a mountain hill towards the valley.
Charla skirts along the surface of a lake as they reach the Charicific Valley. She mentions its history and how the Charizard train naturally without humans by battling each other, the intense competition making them the strongest worldwide. Misty thinks that it would be too intense for Ash's, but Ash overhears the remark as Charizard arrives, except Charizard is no longer flying but is rather carrying Ash on his back and is left exhausted. Ash and Charizard try to prove their strength, but Charla and Liza note that only weak Charizard show off, suggesting that Ash's needs serious training. Charizard fires a Flamethrower to disprove, but it sets Ash on fire as he runs down the stairs and plunges into the lake. Ash charges up the stairs angrily, taking her comments as an insult as Charizard continues to demonstrate power. Ash wants to battle, pointing at Charla, but Liza mentions that it is her personally trained Pokémon, having raised it since it was a Charmander. Ash and Charizard want to battle the ones in the valley, so Liza opens the large doors, showing all the Charizard, some sleeping, some sparring, and some performing other activities. A few glance at Ash's Charizard as Ash and Charizard are stunned at their larger size. One larger Charizard walks by and Liza points out that if Charizard can defeat that one, it may qualify to join.
Charizard is quick to march up behind it and blast it in the face with Flamethrower. The wild Charizard literally inhales the attack and retaliates with its own, leaving Ash's toasted and it collapses. Charizard gets back up and shakes off the dust as Liza points to one sleeping, mentioning that despite the fact it is larger than Ash's it is still the most gentle of the Charizard. Charizard confronts that one and fires another Flamethrower, but the wild Charizard hardly reacts and turns away. However, the wild Charizard quickly lashes its tail, and Charizard is tossed against a wall. After it hits the ground, Charizard struggles to get up, Liza noticing that it is not strong enough to even match. Ash tries to console Charizard, that it will always be good enough for him, but Charizard charges for another attack, but another lash knocks it down. Ash tries to call Charizard off and the others try to convince it to give up, but Charizard continues to get beaten, eventually getting tossed out of the gate and down the stairs. Ash's friends are shocked at how the gentle one could still easily beat down Charizard. Charizard struggles to climb up the stairs however Liza closes the gates, kicking Ash and Charizard out of the valley telling Charizard to return after some training. Charizard smacks on the gate continually. Team Rocket, watching from a distance, realized that they can't capture any of the Charizard because Ash's Charizard, which always beats them, was easily defeated by those Charizard, and the machine they bought is weak. Liza reopens the gates and tells Charizard to go with Ash and that it can return after some training, but Charizard stubbornly refuses. Liza lets Charla battle and Ash's Charizard is tossed into a lake. Ash and his friends know how much Charizard hates the water as Liza tells Charizard to stay put and reflect before closing the gate.
Charizard stares at the gate upset, roaring a cry as Team Rocket sympathizes with the Pokémon. When night falls, Misty notes how Charizard literally stayed in place since that afternoon. Ash wants to leave, but Charizard doesn't. Ash knows that Charizard wants to get stronger and ultimately the decision is up to Ash. Team Rocket watches as Meowth translates Charizard's thoughts about wanting to be stronger. Throughout the night, Ash and his friends fall asleep, but Team Rocket tosses rocks at Charizard to keep it awake and prevent its flame from fading. Through the gates, Liza and Charla note how Charizard's determined to get in.
The next morning, Ash wakes up and sees Charizard still sitting there. Ash knows what Charizard wants to do and knows that it would be wrong to not honor it. Team Rocket's mecha shows up and rolls up to the gate, planning to try to break in. Everyone notices as Charizard gets up and flies towards the mecha. Charizard confronts them and blasts them with Flamethrower, overheating the mecha and making it explode, sending Team Rocket blasting off as they planned. Ash and his friend applaud as the gate opens, Liza applauding and inviting Charizard in. Ash wonders why beating Team Rocket qualifies, but Liza points out that Charizard proved that it wants to enter. The other Charizard and Charla roar and Ash knows what he has to do now. Shocking his friends, Ash angrily tells Charizard it should stay if it wants to because he'll get along just fine without it... and then adds that he doesn't really want a weak Charizard anyway. Ash starts to walk away and points to the valley, telling Charizard that it's got a lot to learn and should get going before Ash starts running away quickly followed by Misty and Brock. Pikachu waits a second with Charizard until it gives a thumbs-up to its long-time teammate, letting it know it understands. Pikachu bids Charizard farewell and starts to follow the group.
With tears in his eyes and knowing he's doing the right thing even though it's hurting him to do so, Ash leaves the Valley and Charizard behind and knowing he might change his mind if he stops, Ash keeps on running...