Ash, Misty, and Brock are traveling through the Johto region when they come across a beautiful, serene lake under a clear blue sky. They are excited to take a break and enjoy the scenery. As they approach the water, they notice a shimmering light reflecting off the surface, which captures their attention. Misty expresses her desire to catch some Water-type Pokémon, while Brock is more interested in the local cuisine.

Suddenly, they encounter a local boy named Kenta, who is fishing by the lake. Kenta is enthusiastic and shares that the lake is known for its rare Pokémon, particularly a special one that appears only during a blue moon. He explains that the blue moon is a rare event that happens once in a while, and it is said to bring good luck to those who witness it. Intrigued, Ash and his friends decide to stay and see if they can catch a glimpse of this rare Pokémon.

As they set up camp by the lake, Kenta reveals that he has been waiting for the blue moon to appear for a long time. He is determined to catch the elusive Pokémon, which he believes will help him become a better trainer. Ash, inspired by Kenta's enthusiasm, vows to help him in his quest. They spend the day fishing and training their Pokémon, with Pikachu and Kenta's Pokémon bonding over their shared goal.

As night falls, the group gathers around a campfire, sharing stories and excitement about the upcoming blue moon. Kenta expresses his hopes and dreams of becoming a Pokémon Master, and Ash encourages him, sharing his own experiences. The camaraderie builds as they all look forward to the night ahead. However, as the moon rises, they notice that it is not blue, but rather a regular full moon. Kenta is disappointed, feeling that his chance to see the rare Pokémon is slipping away.

Just as Kenta is about to give up hope, the moon begins to change color, transforming into a stunning blue hue. The group is filled with awe and excitement, realizing that the blue moon is indeed happening. They quickly gather their Pokémon and prepare to witness the magical event. As the blue moon shines brightly, the water in the lake begins to ripple, and a mysterious figure emerges from the depths.

The figure turns out to be a beautiful, ethereal Pokémon known as a Lanturn. The group is mesmerized by its glowing presence, and Kenta is determined to catch it. He throws a Poké Ball, but Lanturn evades capture, swimming gracefully around the lake. Ash and Misty encourage Kenta to work together with his Pokémon to strategize a better approach. They all join forces, using their Pokémon to create a distraction while Kenta prepares to throw another Poké Ball.

In a tense moment, Kenta finally manages to throw the Poké Ball at Lanturn, but it breaks free once again. The group realizes that Lanturn is not just a Pokémon to be caught; it is a symbol of the beauty of the moment and the bond they share. Kenta, understanding this, decides to let Lanturn go free, appreciating the experience rather than focusing solely on capturing it.

As the blue moon begins to fade, Lanturn swims away, leaving behind a trail of sparkling light. Kenta feels a sense of fulfillment, having witnessed the rare Pokémon and learned an important lesson about friendship and respect for Pokémon. The group shares a heartfelt moment, celebrating their adventure and the memories they created together.

With the blue moon setting, Ash, Misty, Brock, and Kenta pack up their camp, ready to continue their journey. Kenta thanks Ash and his friends for their support and vows to keep training hard. They all part ways, inspired by the magical night and the bonds they formed, looking forward to their next adventures in the Johto region.

In the ending of "Once in a Blue Moon," Ash, Misty, and Brock witness the rare appearance of a blue moon, which brings out a special Pokémon, the blue-colored Hoothoot. They help a young Hoothoot reunite with its mother, showcasing themes of friendship and the bond between Pokémon and their trainers. The episode concludes with the trio reflecting on their adventure under the beautiful blue moon.

As the episode nears its conclusion, the scene shifts to a serene night sky, where the blue moon casts a magical glow over the landscape. Ash, Misty, and Brock stand together, their faces illuminated by the soft light. They are filled with a sense of wonder and accomplishment after their journey to help the young Hoothoot.

Earlier, the trio had encountered a young Hoothoot that had lost its way. The little Pokémon was distressed, flapping its wings anxiously as it searched for its mother. Ash, with his characteristic determination, immediately took it upon himself to help. Misty, always empathetic, comforted the young Hoothoot, while Brock used his knowledge of Pokémon to guide them in their search.

As they ventured deeper into the woods, they faced various challenges, including navigating through thick underbrush and overcoming their own fears. Each character's internal motivations shone through: Ash's unwavering resolve to protect Pokémon, Misty's nurturing spirit, and Brock's calm, strategic thinking. Their teamwork was crucial as they worked together to find the Hoothoot's mother.

Finally, after a series of heartwarming and tense moments, they spotted the mother Hoothoot perched on a branch, calling out for her lost child. The reunion was emotional, with the young Hoothoot chirping joyfully as it flew into its mother's embrace. The scene was filled with warmth, emphasizing the bond between Pokémon and their families.

As the blue moon rose higher in the sky, Ash, Misty, and Brock took a moment to reflect on their adventure. They shared smiles, feeling a deep sense of fulfillment from their good deed. The episode closed with the trio looking up at the blue moon, a symbol of hope and the magic of friendship, as they prepared to continue their journey together. Each character felt a renewed sense of purpose, ready to face whatever challenges lay ahead, united by their shared experiences and the bonds they had strengthened.

In the episode "Once in a Blue Moon" from Pokémon's third season, there is no post-credit scene. The episode concludes without any additional content after the credits roll. The focus remains on the main storyline, which revolves around Ash, Misty, and Brock encountering a rare Pokémon, the Blue Moon, and the emotional journey they experience throughout the episode. The narrative wraps up with the resolution of the main plot, leaving no further scenes or additional content after the credits.

In 'Once in a Blue Moon', the special event is the appearance of a rare blue moon, which is said to have magical properties that can affect Pokémon.

Ash encounters a wild Hoothoot, which is central to the plot as it is believed to be affected by the blue moon's magic.

Misty expresses excitement and wonder about the blue moon, feeling that it brings a sense of magic and possibility, especially regarding the Pokémon they might encounter.

Team Rocket tries to capture the rare Pokémon that appear during the blue moon, believing they can use its magic to their advantage and steal Ash and his friends' Pokémon.

By the end of the episode, Ash and his friends learn about the importance of respecting nature and the magical moments it can bring, as well as the bond they share with their Pokémon.

The episode "Once in a Blue Moon" from Pokémon's third season, "The Johto Journeys," is generally considered family-friendly. However, there are a few elements that might be slightly concerning for very young or sensitive viewers:

1. Emotional Moments: The episode features themes of longing and separation, particularly related to the bond between Pokémon and their trainers, which may evoke feelings of sadness or empathy.

2. Conflict: There are scenes of rivalry and competition, which may include some tension between characters. This could be perceived as upsetting for children who are sensitive to conflict.

3. Mild Frightening Imagery: Some Pokémon may appear intimidating or cause brief moments of surprise, which could be unsettling for very young viewers.

Overall, while the episode contains emotional depth and moments of conflict, it remains suitable for a family audience.