You've no need to stitch your shadow to your heels

This is more a "I got the urge to talk about this so I'm gonna make a blog post about it to get it out of my system" kind of thing.

So I'm gonna talk about the names of the player characters in Pokémon games.

Gen 1 (Red/Green/Blue/Yellow) - The official name of the Gen 1 main character is Red. His rival is known as Green in the Japanese version, and Blue in the international version. The reason for the difference is that the original two games released in Japan were Pokémon Red Version and Pokémon Green Version. A third game, named Pokémon Blue Version, was later made, which fixed some bugs and other problems with the original two games. This game became the basis for the international Gen 1 games, which were released as Pokémon Red Version and Pokémon Blue Version, with the original Pokémon Green Version never getting an English release until the remakes Pokémon FireRed and Pokémon LeafGreen came out. (The title Pokémon WaterBlue was trademarked, but no such game was ever released). The remakes also added the option to play as a female protagonist, whose official name is Leaf.

In the original Gen 1 games, when beginning the game, the player is able to select from a list of three names or choose their own. The names provided are:
Red - Red, Satoshi/Ash (Satoshi in the Japanese version, Ash in the international version), Jack
Green/international Blue - Green/Blue, Shigeru/Gary, John
Japanese Blue - Blue, Tsunekaz, Jean
Yellow - Yellow, Satoshi/Ash, Jack
The second names in the lists are tributes to real people. Satoshi after Tajiri Satoshi, the creator of the Pokémon franchise; Shigeru from Miyamoto Shigeru, a game director at Nintendo who encouraged Satoshi to make the series; and Tsunekaz after Ishihara Tsunekazu, president of The Pokémon Company. The names Satoshi/Ash and Shigeru/Gary were later used for the main character and his rival in the Pokémon anime, which is considered a separate continuity from the games.

In FireRed and LeafGreen, if the player enters no name when prompted, Professor Oak will select from a list of 27 randomly chosen names. The names that can be chosen from are (names separated with a slash indicate differences between Japanese and English versions): Green, Red, Leaf, Fire, Shigeru/Gary, Tsunekaz/Kaz, Satoru/Toru, Satoshi/Ash, Ken/Kene, Shigeki/Geki, Jack/Jak, Jean/Janne, John/Jonn, Kamon, Takashi/Karl, Tetsuo/Taylor, Tōru/Oscar, Hiroki/Hiro, Masao/Max, Takao/Jon, Takehiro/Ralph, Kei/Kay, Hitoshi/Tosh and Hiroaki/Roak.

Until Gen II was released, the Gen I main character was officially named Satoshi. After Gen II came out, his name was changed to Red, possibly to make it clear that he was a separate character from the anime's protagonist, Satoshi.

The Japanese manuals for the Gen 1 games mention the name of the main character and his rival, but give different names for each version: Red and Green (for hero and rival respectively) in Red Version, Green and Red in Green Version, Blue and Red in Blue Version, and Yellow and Blue in Yellow Version.

Hidden data in the English versions of the original games shows some placeholder names: Ninten for the main character and Sony for his rival, referencing the rivalry between Nintendo and Sony at the time. Ninten is also the name of the main character of the game Mother, which was developed by Creatures, Inc., who are affiliated with The Pokémon Company.

The Japanese games, meanwhile, contain some different unused names hidden in the data: Yamaguchi for the main character (a reference to Yamaguchi Wataru, an art director who worked on the games) and Ishihara for the rival (referencing Ishihara Tsunekazu). In Japanese Blue, the unused default names are Gēfuri for the hero (an abbreviation of Gēmu Furīku, or Game Freak, the company responsible for developing the game) and Kuricha for the rival (a reference to Creatures, Inc.).

Gen II (Gold/Silver/Crystal) - The male main character is named Hibiki in Japanese and Ethan in English, and the female protagonist in Crystal is named Kris in both versions. In the remakes, HeartGold and SoulSilver, the female is named Kotone in Japanese and Lyra in English. In all Gen II games (including remakes), the rival is named Silver in both versions.

The Japanese manuals for the Gen II games refer to Ethan as Gold in Pokémon Gold and Silver in Pokémon Silver. The Japanese manual for Pokémon Crystal uses the name Kris for both the male and female player characters.

In Pokémon Crystal, the first default name for both male and female protagonists is クリス (Kurisu). In the English version, this was romanised as Chris for the boy and Kris for the girl.

Two image files from Game Freak's Japanese website referred to the female character as Clis, an alternate romanisation of クリス (Kurisu).

Gen III (Ruby/Sapphire/Emerald) - In all versions (including the remakes Omega Ruby and Alpha Sapphire), the male main character is named Yūki in Japanese and Brendan in English, and the female is Haruka in Japanese and May in English. Whomever you choose, the other will function as your rival, though the games also introduce a second rival, a boy named Mitsuru in Japanese and Wally in English.

Gen IV (Diamond/Pearl/Platinum) - In all versions (including remakes Brilliant Diamond and Shining Pearl), the boy is named Kōki in Japanese and Lucas in English, and the girl is named Hikari in Japanese and Dawn in English. The rival is named Jun in Japanese and Barry in English.

The Japanese Nintendo website contains screenshots of Pokémon Platinum that refer to Dawn as Tina.

Internal game data refers to Barry as Pearl in the Japanese version and Cedric in the English version. His default name is either Diamond or Pearl, depending on which version you're playing. Barry was used as his official name in Pokémon Masters EX, as well as for his counterpart in the English dub of the anime.

Gen V (Black/White) - The male is named Touya in Japanese and Hilbert in English, and the female is named Touko in Japanese and Hilda in English. In the sequels Black 2 and White 2, the boy is named Kyōhei in Japanese and Nate in English, and the female is named Mei in Japanese and Rosa in English. The male rival is named Cheren in both languages, and the female rival is named Bel in Japanese and Bianca in English. In the sequels, the rival's name is Hugh in both languages.

Prior to the release of the games, fans and most media referred to Hilbert and Hilda as Black and White respectively. Early English demos of the game referred to them as Blair and Whitlea, and English pre-release screenshots referred to them as Kuro and Shiro, Japanese for "black" and "white".

Cheren's name is the Bulgarian word for "black". Bianca's Japanese name, Bel, comes from the Macedonian word for "white", and may also be a pun on "belle", French for "beautiful". 

Pre-release media for the sequels referred to Nate and Rosa as Black2 and White2 respectively.

Gen VI (X/Y) - The male is named Calme in Japanese and Calem in English, and the female is named Serena in both languages. Whomever you choose, the other will function as your rival. The Gen VI games also have three additional rivals - a girl named Sana in Japanese and Shauna in English, an older boy named Tierno in both languages, and a younger boy named Trova in Japanese and Trevor in English.

Pre-release media referred to Calem and Serena as X and Y respectively in Japanese, and as Xavier and Yvonne respectively in English.

Calme is French for "calm", and Serena comes from the word "serene". Sana means "healthy" in Latin and "brilliance" in Arabic. Tierno means "tender" in Spanish. Trova comes from the Italian "trovare" meaning "to find" or "to discover", and Trevor is a pun on "trouver", French for "to find".

Gen VII (Sun/Moon) - In all versions (including the remakes Ultra Sun and Ultra Moon), the male main character is named Yō in Japanese and Elio in English, and the female is named Mizuki in Japanese and Selene in English. The games also have two rivals, both male. The younger one is named Hau in both languages, while the older one is named Glazio in Japanese and Gladion in English.

In the Gen VII games, it is heavily implied that the player characters are originally from Kanto, the region where the Gen I games take place. This is backed up by them having Japanese names in the Japanese versions, since the Kanto region is based on Japan.

In both languages, the names of the main characters are relevant to the games. Yō comes from "taiyō", Japanese for "sun", and Elio is a reference to Helios, the Greek god of the sun. Mizuki means "beautiful moon" in Japanese, and Selene is the name of the Greek goddess of the moon.

Some pre-release media referred to Elio and Selene as Sun and Moon respectively, though the names Elio and Selene were also used in pre-release media. Elio and Selene were later used as their official names in Pokémon Masters EX. Pre-release media for the remakes referred to them as Kouta and Koumi in Japanese, and Ray and Ailey in English. Unused internal data refers to them as Kai and Lana, which mean "ocean" and "afloat" in Hawaiian.

Hau is the Hawaiian name for Hibiscus tiliaceus, commonly known as sea hibiscus (among many other names), a flower common in Hawaii.

Glazio and Gladion both derive from Gladiolus, a genus of flowering plants in the iris family sometimes called sword lilies.

Gen VIII (Sword/Shield) - The male main character is named Masaru in Japanese and Victor in English, and the female is named Yuuri in Japanese and Gloria in English. There are also three rivals - a younger male rival named Hop in both languages, an older male named Beet in Japanese and Bede in English, and a female named Mary in Japanese and Marnie in English. The DLC expansion pass Yoroi no Kotō/The Isle of Armor introduces two more rivals, a female named Klara in both languages and a male named Savory in Japanese and Avery in English.

Pre-release media used the names Sword and Shield for Victor and Gloria respectively, though the names Victor and Gloria were also used in pre-release media.

Masaru means "to surpass" in Japanese, and Yuuri derives from "yū", meaning "excellent". The Japanese names also form a pun, as the kanji of the two names can be combined together to make "shōri" (victory) or "yūshō" (championship). The English names Victor and Gloria refer to victory and glory, respectively.

Like in Gen VII, the main characters have Japanese-sounding official names in the Japanese version, possibly indicating they too originally came from Kanto.

Bede's Japanese name refers to Beta vulgaris, a flowering plant commonly known as beet, from which the vegetable beetroot is taken. His English name is the name for the same plant in Danish, though it could also just be a slight alteration of the Japanese name.

Klara takes her name from kurara, the Japanese name for Sophora flavescens, a shrub commonly known as the shrubby sophora.

Gen IX (Scarlet/Violet) - The male main character is named Haruto in Japanese and Florian in English, and the female main character is named Aoi in Japanese and Juliana in English. The rival is a girl named Nemo in Japanese and Nemona in English.

Gen IX is the first game in the series where both the male and female main characters wear the same outfit.

The characters are never named in game, but they were referred to as Florian and Juliana in pre-release media and material. English material also sometimes referred to them by their Japanese names, Haruto and Aoi.

"Haru" means "spring" in Japanese (or figuratively "prime of life"), and "aoi" literally means "blue/green" but can also be used figuratively to mean young or inexperienced. If the kanji for "haru" and "aoi" are put together, they form the word "seishun", meaning "youth".

Nemona is the first rival to have completed her journey prior to the events of the game. She's also the first female rival to be the only rival in the game, regardless of the player character's gender. Her name derives from the Nemophila genus of flowering plants, many of which are commonly known as "baby blue eyes".

Other games:

In Pokémon: Let's Go, Pikachu! and Let's Go, Eevee!, which are loose remakes of the Gen I games (particularly Pokémon Yellow), the male player character is named Kakeru in Japanese and Chase in English, and the female is named Ayumi in Japanese and Elaine in English. Whomever you play as, the other will function as your rival.

"Kakeru" means "to dash" in Japanese, and "ayumi" means "step" or "progress".

The main characters of Pokémon Legends: Arceus are a boy named Teru in Japanese and Rei in English, and a girl named Shō in Japanese and Akari in English.

The player characters of Pokémon Legends: Arceus are the only protagonists in the series to have voice acting.

"Teru" and "shō" both mean "to shine" in Japanese. Their English names are also light-related - Rei sounds like ray, as in a ray of light, and "akari" means "light" in Japanese (and is also similar to "Hikari", Dawn's Japanese name).

The main character of Pokémon Stadium, which was only released in Japan, is an unnamed boy. The same boy appears as the main character of Pokémon Stadium 2, which was released internationally as Pokémon Stadium. Pokemon Stadium Kin Gin, released internationally as Pokémon Stadium 2, has an unnamed girl as the main character.

The main character of Pokémon Colosseum is a young man named Leo in Japanese and Wes in English.

As with the Gen I games, the game gives you three options for the main character's name. These are Leo, Yūta and Tatsuki in Japanese, and Wes, Seth and Thomas in English.

The main character of Pokémon XD Yami no Kaze Dark Lugia, released internationally as Pokémon XD: Gale of Darkness, is a boy named Ryūto in Japanese and Michael in English.

As in the previous game, three default name options are given. These are Ryūto, Jaime and Retsu in Japanese, and Michael, David and Adam in English.

The main characters of Pokémon Battle Revolution are a boy named Jay in Japanese and Nate in English, and a girl named Rin in Japanese and Cyndy in English.

The main characters of Pokémon Go are an unnamed boy and girl.

The main characters of Pokémon Masters EX, originally released as Pokémon Masters, are a boy named Kei in Japanese and Scottie in English, and a girl named Yui in Japanese and Bettie in English.

The main characters of Pokémon + Nobunaga no Yabō, released internationally as Pokémon Conquest, are an unnamed male and female, referred to as Shujinkō (literally Protagonist) in Japanese and as Hero and Heroine respectively in English.

The main characters of Pokémon Ga-Olé are an unnamed boy and girl.

The main characters of Pokémon Ranger are a boy named Kazuki in Japanese and Lunick in English, and a girl named Hinata in Japanese and Solana in English.

The names in both languages refer to the sun and moon. Kazuki comes from tsuki, Japanese for moon, and his English name is derived from luna, the Latin word for moon. Hinata comes from "hi" meaning "sun" and "hinata" meaning "sunny place", and her English name from sol, Latin for sun.

Note: In Japan, Pokémon Yellow is simply referred to as Pocket Monster: Pikachu (Pocket Monster being the Japanese name for the series, which was shortened to Pokémon in English), and doesn't actually mention a colour in the title. The official English title is Pokémon Yellow Version: Special Pikachu Edition, though it's often shortened to simply Pokémon Yellow Version.