The Pokémon franchise has many characters and Pokémon that are minimal in one form of media but become important in others. Anime & Manga adaptations tend to do this. Any important NPC will probably have some plot significance for at least a chapter.
The games
- In Pokémon Platinum, HeartGold, and SoulSilver, Caitlin just sat in a throne in the Battle Castle, never even battling you. In Pokémon Black and White, she's a member of the Elite Four!
- In the original Pokémon Gold and Silver, the Kimono Girls are only found in the Dance Theater in Ecruteak City. Defeating them and their Eeveelutions in battle earns the player HM04 (Surf), but that's it. In the HeartGold and SoulSilver remakes, they're encountered both individually and collectively throughout Johto, and in ways that are actually plot-relevant. They also Took a Level in Badass, with their Pokémon going from level 17 to 38.
- And the guide guy who stands in front of each Gym and tells you about its type is now a named character, Clyde, who gives you a bottle of Fresh Water before every challenge.
- While how much a Legendary Pokémon could be considered an "extra" may be up to debate, Rayquaza, Giratina, Kyurem and Necrozma went from barely or never mentioned in the plot of their debut games and the wild Mons equivalent of an Optional Boss to much more important in the third version / sequel of their respective generations.
- Zygarde is an unusual case as it was initially presented as one of these, but it never became the star of a third version (Game Freak opted to remake Ruby and Sapphire). Instead, it became a little more prominent in Pokémon Sun and Moon and had a whole sidequest dedicated to it, but it still isn't the main focus.
- Since its debut in Ruby/Sapphire/Emerald, Deoxys was a Mythical Pokémon - a Pokémon only attainable through real life events, and all but impossible to get if you play the game after the event(s) passed/live in an area with no Wi-Fi connection* . Furthermore, its presence was almost entirely ignored in the stories of the games. However, in Omega Ruby/Alpha Sapphire, Deoxys is elevated to the status of Final Boss at the end of the brand new Delta Episode, and is now catchable no matter where or when you play the game.
- Other Mythical Pokémon that have since received this treatment include Celebi (now freely available after beating the Elite Four in the Virtual Console version of Crystal), Keldeo (as a hidden fight in the Crown Tundra DLC of Sword and Shield), and Arceus (as the central Pokémon and final boss of Legends: Arceus).
- Pokémon Ultra Sun and Ultra Moon does this to a few characters that were merely side characters in the original Pokémon Sun and Moon games. For example, Mina, a Trial Captain hadn't invented her own trial in the original games and just gave you her Z-Crystal. In the Ultra games, she has her own established trial. On the flip side, a few characters who were more prominent in Sun and Moon were Demoted To Extras.
- Originally just an ordinary Pokémon (albeit one with a memorable evolution mechanic), Eevee slowly began to receive more attention over the years as a result of its Ensemble Dark Horse status; this, among other factors, led to its role as one of the default starter Pokémon in Pokémon Let's Go, Pikachu! and Let's Go, Eevee!.
- Professor Burnet was a character in a minor spinoff game from the launch of Pokémon Black 2 and White 2 entitled Pokémon Dream Radar. Come Sun & Moon and she plays a major role and is revealed to be married to the region's professor, Professor Kukui.
- Also in Sun & Moon, Anabel, one of the Frontier Brains from Emerald who didn't appear in Omega Ruby & Alpha Sapphire has become an international police officer and boss of Looker.
- Looker debuted in Platinum and reappeared in Pokémon Black and White, but his roles became bigger and bigger in Pokémon X and Y and Sun & Moon. However he and Anabel had been demoted to extras in Ultra Sun & Ultra Moon.
- Unless you do the Battle Subway, it's possible to go the entirety of Pokémon Black and White without ever meeting either of the Subway Bosses. Pokémon Black and White 2 remedies this slightly by having an overworld Double Battle against the both of them, but they're still inconsequential to the game. Come Pokémon Legends: Arceus however, and it's revealed that Ingo, the older twin, is one of the Pearl Clan Wardens and appears to have lost his memories from being sent back in time.
Pokémon: The Series:
- Misty and Brock would qualify as this, as in Pokémon Red and Blue they merely appeared as the first two Gym Leaders, while in the first few seasons of the anime they were main characters. In later series, the show repeats this with Cilan and Iris from Pokémon Black and White, Clemont from Pokémon X and Y, and Trial Captains Kiawe, Lana, Mallow, and Sophocles from Pokémon Sun and Moon.
- Speaking of Clemont, his annoying little sister Bonnie: in the games, her only roles are hosting the Lumiose Gym/Prism Tower Pokémon Quiz. After becoming the Champion, the player can get a ribbon from her if they have a Pokémon with maximum affection. In the anime, she's a main character alongside Clemont.
- The Snake Oil Salesman who tries to sell you a Magikarp only makes bit appearances in the Kanto and Unova games, but is a recurring character in the anime.
- Pikachu was merely an average Pokémon in Pokémon Red and Blue. It was then chosen as the mascot of the entire franchise and given a starring role in the anime.
- In Pokémon Sun and Moon, Samson Oak only appears on the third island, and has a fairly minor role in the story as a wholenote . In the anime adaptation on the other hand... he appears as the principal of the Pokémon School and appears far more often as a result.
- Zygarde. In the games it has been a postgame Legendary encounter in Pokémon X and Y and That One Sidequest in Pokémon Sun and Moon and was never given a follow up game to X and Y similar to other Legendary Pokémon in the past and future. The anime however had done it justice and gave it much significance in the XY&Z arc.
- Matori was a very minor character in earlier series, existing mostly as Giovanni's secretary and to update the Team Rocket trio on current agendas; even her debut was at the end of the Diamond & Pearl series. Come Sun and Moon and Matori is upgraded into a Sitcom Arch-Nemesis for Jessie, and sometimes pulls off heists herself with her own squad of Rocket grunts. Matori has even more involvement in Journeys.
- After just having occasional appearances alongside Delia Ketchum since joining her, Mimey was escalated to a recurring character for the Journeys series.
Pokémon Adventures
- Green was initially nothing more than an unnamed female character on the cover of an official Strategy Guide of Pokémon Red and Blue. Adventures turned her into a main character and even gave her more backstory than Red and Blue.
- Adventures has this with nearly every Gym Leader, and quite a few other people.
- A noticeable example is Courtney, a Team Magma admin. She never appeared in the anime, never appeared in any other manga, doesn't have any official art, was fought once, and never appeared in the timeline canon Emerald. But she's the most developed of the admins for either team, maybe even more-so then the leaders.
- Some NPCs in-game like Fisherman Wilton or Swimmer Jack are given significant focus. It might have something to do with both of their name being "Hidenori" in Japanese, the name of the mangaka.
- For an "in house" example there's Professor Yanase who initially was just a scientist on the control Rayquaza project and later is revealed to be Yanase Berlitz, Platinum's mother.
- Marvin in the SWSH arc, who goes from a one-off Trainer in Route 3 to what's essentially the tritagonist of the arc.
