The gang arrives on a new island to witness the Conley Comet. Alexa shares with them the legend of the island. Later, a mysterious woman gives them a medal as they explore the ruins. After the usual run in with Team Rocket, the gang is then attacked by Gengar and Banette. They are then chased by them and Ash drops the medal the mysterious woman gave him. The Gengar, Banette and Dusknoir eventually realize it's the Hero Conley's Medal and accept Ash and the others as friends.
They then take them to the battlefield where Hero Conley battled and show them the comet. Team Rocket then tries to take Pikachu from Ash, but the gang of Ghost Pokémon stops them with their Psychic attack. Pikachu is returned to Ash, and he, Cilan, and Iris dance below the comet with the Ghost Pokémon.
The next day, the gang discovers the Hero Conley's Medal has vanished with all of Alexa's footage, which is replaced with static. The mysterious woman's revealed to have been a friend of the Hero Conley, leading the gang to speculate about her identity.
The heroes have arrived at the island. Alexa anticipates the night, when the Conley Comet will be passing through the sky. She also heard some Pokémon gather at the island's mountain to witness the moment. Iris wonders why is that the case, but Alexa is determined to find out. They arrive at the ruins, which Alexa remembers they were built by people, who lived and prospered on the island. She advises to have dinner right away. During the meal, Alexa remembers there were reports of Pokémon attacking the humans. The people surrendered, but a trainer came and subdued the attacks, saving the islanders. Alexa tries to find a book about it, but panics, as she throws away the stuff from the bag. Helioptile opens the other bag, showing the book was in there.
Alexa shows them the picture of the hero. She remembers the story: as the islanders were attacked by the ghost Pokémon, the hero, Conley, appeared, and let the Pokémon to the top of the mountain. There, he called the power of the comet, striking the ghost Pokémon. The ghost Pokémon felt as Conley knew about the comet's existence, but nevertheless they calmed down and befriended Conley. Trainers around the world went to the island to challenge Conley, so he constructed an arena at the top of the mountain. It is said Conley never lost, and to this day, the comet still bears his name. While Alexa plans on taking footage at the arena, Team Rocket intends on catching Pikachu. Before they go to the mountain, the heroes are approached by a woman, who gives them an medal with a star sign. The woman asks them to be cautious and walks away, without any other word. Alexa has a feeling she saw this medal, but dismisses it and go to the top.
Team Rocket puts on costumes of Gengar, Dusknoir and Banette, planning on scaring the heroes away to catch Pikachu, but are observed by someone else. As the heroes travel towards the top, Pikachu senses something, but dismisses that. Soon, the heroes are at the arena and enter it. They admit it is dark and Iris gets scared by Woobat. Ash thinks it is no reason to be afraid, but gets scared by Venipede, prompting Iris to call him a little kid for that. Ash is angered and yells at her. Team Rocket, dressed as ghosts, hide behind the statue. The heroes enter the room and see the statue of Conley. Cilan thinks the statue's presence symbolizes respect the Pokémon and islanders gave for Conley. Alexa goes to inspect the statue, but finds a Dusknoir, a Banette and a Gengar.
Helioptile is scared and electrocutes them. Team Rocket is knocked onto the statue, causing it to fall down. Jessie is enraged and throws the statue away. Team Rocket, seeing they are discovered, remove their disguises. James goes to send Amoonguss, but he, Jessie and Meowth are stopped by a psychic power. The heroes see Gengar and Banette using Psychic on Team Rocket. The ghost Pokémon stop their Psychic attack, causing Team Rocket to fall down, as the ghost Pokémon levitate around them. Alexa sends a Noivern, who uses Dragon Pulse, defeating the ghost Pokémon. The heroes and Team Rocket run off in the dark corridors. Alexa is relieved everyone is okay. Ash admires Noivern, who actually bites Meowth. Alexa decides to give Noivern a berry, but Meowth eats it. However, the berry is too spicy for him, turning him red. Alexa admits that was a Spelon Berry, known as the spiciest berry around. Alexa gives Noivern a different Spelon Berry, replying Noivern can start biting around if hungry.
Team Rocket wants to know why they were attacked by Gengar and Banette. Cilan suspects they are here to gaze at the comet. The heroes realize since these ghosts are tied to Conley, it is because of Team Rocket the ghosts attacked. Team Rocket is outraged of such a statement, but is reminded they threw the statue of Conley away. The ghosts come back and use Night Shade and Shadow Ball. They also encounter Dusknoir, so the heroes and Team Rocket split into two ways. Cilan, Iris, James and Jessie run through the corridor and argue with each other. Iris believes if they turn the statue back in its place, the ghost Pokémon may calm down. Pikachu uses Thunderbolt, hitting the Gengar, but Dusknoir appear as well. Meowth is hit by a Shadow Ball and knocks Ash down, who drops the star medal. Gengar and Dusknoir surround the medal, so Meowth translates these Pokémon do not believe these people are mean, since they have Conley's medal. Meowth translates the ghost Pokémon decide to bring Ash to the battle field.
Jessie, James, Cilan and Iris place the statue back in its position. Banette arrive back and are pleased the statue is back. Cilan notices the picture of Conley, as a door opens, and they all are taken away, as the statue is moving away. Ash, Alexa and Meowth arrive to the battlefield, where they meet up with Iris, Cilan, James and Jessie. Cilan suspects these are the ghosts that Conley befriended, while Ash shows they stopped their attacks when he showed the medal. Suddenly, Team Rocket grabs Pikachu with a cuff and traps him, then flies off in the balloon. However, they are being pulled by the ghost-type Pokémon back to the arena.
Pikachu is freed, while Jessie sends Frillish, who uses Bubblebeam and James, whose Amoonguss attacks with Hidden Power. Alexa sends Noivern, who counters the attacks with Boomburst, while Pikachu blasts Team Rocket off with an Electro Ball. Alexa praises Noivern and gives it the berry. A bright light shines on the sky, as the Conley Comet appears in the sky. The ghost-type Pokémon are glad and start dancing. The woman, who gave Ash the medal, appears and clarifies the ghosts celebrate the day they encountered Conley. Alexa wonders who the woman is and what is she doing. The woman is Anima, who knows the past and the future, admiring the Pokémon's will to celebrate the day. Ash, Iris and Cilan join in and dance as well, with Alexa recording this.
Next day, the heroes are pleased they experienced many things. Alexa goes to check the video, but has nothing but static. Cilan and Iris see it is strange such a thing has happened, while Ash does not have the medal anymore. Alexa remembers something and shows the book again, with Anima, Conley and the gold medal. The heroes are surprised, wondering whom they actually saw.
"Who's that Pokémon?": Banette
Despite being a-type Pokémon, Meowth was hit by a Shadow Ball, a move he normally is immune to.