His lifelong rival is Gary Oak. When he became 10 years old, he was to receive his first pokémon. He overslept and by the time he arrived at Professor Oak's Laboratory, all the starter pokémon (Bulbasaur, Charmander, and Squirtle) had been taken and he had to start with a Pikachu instead. His Pikachu has the particular characteristic of hating pokéballs so it always tags along with Ash.
His last name Ketchum is believed to be a pun on the phrase "catch'em".
Ash, like most Pokémon Trainers, aspires to be the greatest Pokémon Master ever. To do this, he goes through the regions battling Gym Leaders to reach the Pokémon League competitions and capturing Pokémon to fill up his pokédex. He started his travel with Misty (Kasumi in Japanese), the Cerulean Gym Leader and Brock (Takeshi in Japanese), the Pewter Gym Leader.
However, his journey hasn't been that easy. Team Rocket (Rocketto Dan) constantly gets in his way trying to steal his pokémon for their own interests.
Ash's Road to the Indigo League:
Pewter Gym
2 vs 2 Elimination—Brock (Onix) d. Ash (Pikachu). Match aborted by Ash.
2 vs 2 Elimination—Ash (Pidgeotto, Pikachu) NC Brock (Geodude/Onix). Match aborted by Ash, but Brock concedes defeat.
Cerulean Gym
2 vs 2 Elimination—Ash (Butterfree, Pidgeotto) NC Misty (Staryu/Starmie). Match interrupted by Team Rocket, Misty's sisters concede defeat, citing that Ash would have won if Pikachu was used.
1 vs 1—Sabrina (Kadabra) d. Ash (Pikachu). Ash forfeits.
1 vs 1—Ash (Pikachu) d. Sabrina (Kadabra). Sabrina was unable to continue due to the antics of Haunter, giving the match to Ash.
Celadon Gym
3 vs 3 Elimination—Ash (Bulbasaur, Charmander) d. Erika (Tangela, Weepinbell, Gloom). Match interrupted by Team Rocket, Erika concedes defeat as Ash had saved Gloom from a fire.
Fuchsia Gym
2 vs 2 Elimination—Ash (Pidgeotto, Charmander) NC Koga (Venomoth). Match interrupted by Team Rocket.
3 vs 3 Elimination—Blaine (Ninetales, Rhydon, Magmar) d. Ash (Squirtle, Charizard, Pikachu). Ash forfeits the match.
1 vs 1—Ash (Charizard) d. Blaine (Magmar).
Viridian Gym
3 vs 3 Elimination—Ash (Squirtle, Bulbasaur, Pidgeotto, Pikachu) d. Team Rocket (Machamp, Kingler, Rhydon, Arbok, Weezing). Match ends when Team Rocket tries to cheat, which ended up with Team Rocket being sent flying, dropping the Earth Badge in the meantime.
Indigo Plateau
Qualifying Round (Water Field), 3 vs 3 Elimination—Ash (Kingler) d. Mandy (Exeggutor, Seadra, Golbat).
Qualifying Round (Rock Field), 3 vs 3 Elimination—Ash (Squirtle) d. an unnamed trainer (Nidorino). Ash wins as the episode begins.
Qualifying Round (Ice Field), 3 vs 3 Elimination—Ash (Kingler, Pikachu) d. an unnamed trainer (Cloyster, Arcanine).
Qualifying Round (Grass Field), 3 vs 3 Elimination—Ash (Bulbasaur, Pikachu, Muk) d. Jeanette Fisher (Beedrill, Scyther, Bellsprout).
Round of 16, 3 vs 3 Elimination—Richie (Butterfree, Charmander, Pikachu) d. Ash (Squirtle, Pikachu, Charizard). Charizard refuses to battle, making Ash forfeit the match.
After ending up among the 16 best in the Indigo Pokémon League, Ash ventured towards the Orange Islands to get a GS ball for Professor Oak. There, he discovered that there were pokémon gyms there as well and took the challenge enthusiastically. A Pokémon Observer named Tracey traveled with them while they were in the Orange Islands.
Ash's road to the Orange League:
Mikan Island Gym
Water Gun Challenge—Ash (Squirtle) draws Sissy (Seadra). A Water Gun Shooting Challenge, both with stationary and moving targets.
Pokémon Wave Ride—Ash (Lapras) d. Sissy (Blastoise). A race where trainers must stand atop their surfing Pokémon.
Navel Island Gym
Geyser Challenge—Danny (Nidoqueen) d. Ash (Lapras). First Pokémon to freeze hot water from a Geyser wins.
Sled Carving—Ash (Pikachu, Bulbasaur, Charizard) d. Danny (Nidoqueen, Scyther, Machoke). First team to carve a sled from the resulting ice pillar wins.
Sled Race—Ash (Pikachu, Bulbasaur, Squirtle) d. Danny (Geodude, Scyther, Electrode). A race down a mountain using the sled.
Trouvita Island Gym
Target Challenge—Ash passes the challenge (knocking down targets while on a moving boat) with Pikachu, Squirtle, Bulbasaur, and Charizard.
3 vs 3 Type Battle—Ash (Pikachu, Bulbasaur, Squirtle) d. Rudy (Electabuzz, Exeggcutor, Starmie). Best two out of three matches, with opposing Pokémon being of the same type.
Kumquat Island Gym
2 vs 2 Double Battle—Ash (Pikachu, Charizard) d. Luana (Alakazam, Marowak). The first Pokémon to faint loses the battle for the trainer (this differs from a Hoenn Double Battle where both Pokémon have to faint).
Pummelo Island
6 vs 6 Elimination—Ash (Pikachu, Squirtle, Lapras, Tauros, Bulbasaur, Charizard) d. Drake (Ditto, Onix, Gengar, Venusaur, Electabuzz, Dragonite).
When he finally returned to Professor Oak, the professor told Ash to venture off into Johto to give the GS ball to Kurt, a famed pokéball expert, and he did so (Tracey stayed with Oak). Upon arriving there, he found out about the Johto League, signed up and started facing the gym leaders from Pokémon Gold, Silver, and Crystal.
Once he finally made it to the Johto League Silver Conference, he beats Gary Oak, but is defeated by Harrison (Hazuki) from Hoenn. Excited, Ash makes his way to Hoenn, but Misty has to leave to take care of the gym and Brock needs to take care of something so he travels alone, leaving all his Pokémon behind except Pikachu.
In Hoenn, he meets up with a trainer called May (Haruka) who travels with him and when they pass through Petalburg City, May's little know-it-all brother Max (Masato) joins them too. They find Brock in Petalburg Forest and continue exploring Hoenn following closely the path players took when playing Pokémon Ruby and Sapphire. This is where the anime episodes currently are.
Ash's Road to the Hoenn League (in progress):
Petalburg Gym
1 vs 1 practice battle—Norman (Vigoroth) d. Ash (Pikachu).
3 vs 3 Elimination—Ash (Pikachu, Torkoal, Grovyle) d. Norman (Slakoth, Vigoroth, Slaking).
Rustbouro Gym
2 vs 2 Elimination—Ash (Treecko, Pikachu) d. Roxanne (Geodude, Nosepass).
Dewford Gym
2 vs 2 Elimination—Brawly (Machop, Hariyama) d. Ash (Taillow, Treecko).
2 vs 2 Elimination—Ash (Treecko, Corphish) d. Brawly (Machop, Hariyama).
Mauville Gym
3 vs 1 Elimination—Ash Pikachu) d. Wattson (Magnemite, Voltorb, Magneton) A robotic Raikou shocks Pikachu, giving it so much power that it defeats all of Wattson's Pokémon in one hit.
1 vs 1 Elimination—Wattson (Manectric d. Ash (Torkoal) This was a unofficial battle to test out their new Pokémon.
Lavaridge Gym
3 vs 3 Elimination—Ash (Corphish, Treecko, Pikachu) d. Flannery (Macargo, Slugma, Torkoal).
Fortree Gym
3 vs 3 Elimination—Ash (Grovyle, Pikachu, Swellow) d. Winona (Swellow(shiny), Altaria, Pikachu—Pikachu was the first Pokémon that Ash obtains, and the only one that has always been with Ash in every adventure. Preferring not to stay in its Pokéball, the two found friendship together.
Caterpie—The first Pokémon that Ash catches, Caterpie is the first Pokémon that Ash has caught without effort.
Pidgeotto—Ash's second Pokemon, caught shortly(after an embarassing start) after Caterpie. Pidgeotto proves most useful to Ash outside of battle, often attacking the hot-air balloons Team Rocket often attacks or escapes in
Metapod—Evolved from Caterpie after a victory against Team Rocket, Metapod was involved in a Pokémon Battle against another Metapod where the only attack that either could use was Harden.
Bulbasaur—Bulbasaur is one of the most senior Pokémon on Ash's team. It is a leader and mediator, preferring peaceful resolutions to conflicts over fighting. Bulbasaur has spent equal time alongside Ash as well as in Pallet Town, where its mediation skills keeps the peace between the many Pokémon that reside there.
Squirtle—Having been abandoned by another trainer, Squirtle was the leader of a group called the "Squirtle Squad". When the Squirtle Squad saves a nearby town from a forest fire, Squirtle joined Ash on his adventures while its fellow squad members formed the town's fire department. Having to return to the Squirtle Squad after seeing his squad members in bad shape (This is because they lack leadership), Squirtle has occasionally returned to Ash's side in some of Ash's more critical battles.
Krabby—The second Pokémon that Ash caught without effort, Krabby was instantly transported to Pallet Town as Ash was carrying six Pokémon with him. Krabby remained in Pallet Town until the first match of the Indigo League championships, where it evolved in its first battle.
Raticate—Having traded Butterfree for this Pokémon, Ash discovers that he missed Butterfree. He quickly returned Raticate for it.
Haunter—Originally following Ash as part of a plan to defeat Sabrina, the Saffron City Gym Leader, Haunter mysteriously disappears when Ash demands rematch after rematch. It is Haunter, ironically, that leads to Ash winning the badge by default. After the battle, Haunter stayed with Sabrina, ending its short tenure with Ash.
Primeape—As a wild Mankey, it had once stolen Ash's hat, upon Ash capturing it, it had already evolved. Primeape's short tenure with Ash ended when it was given to another trainer so that Primeape could take part in the P-1 competitions.
Muk—Muk is one of Ash's Pokémon that spends time back home with Professor Oak. It is very affectionate towards both Ash and Professor Oak, as Muk is often seen smothering Professor Oak.
Tauros—Unintentionally caught while attempting to catch other Pokémon in the Safari Zone, Ash has thirty of such Pokémon, although only one or two have been seen alongside Ash.
Charizard—Charizard is one of the larger Pokémon on Ash's team. Although initially disobedient, it starts to obey and cooperate when its life was in danger, thanks to a battle against a water Pokémon. Since then, Charizard dedicated itself to becoming better, leaving Ash on good terms in Johto. Charizard has occasionally returned to Ash so that it could enter in some of Ash's more critical Pokémon battles.
Kingler
Pidgeot—Evolving from Pidgeotto shortly after Ash returns to Pallet Town from his loss at the Indigo League, Pidgeot left Ash's team to defend a group of Pidgey and Pidgeotto from a group of Fearow that was terrorizing them.
Beedrill—Ash catches Beedrill as part of a bug-catching competition in Johto. With Ash winning the competition, he received Beedrill to keep, and promptly gave it away to Casey, who had an affection for yellow striped Pokémon.
Phanpy—The youngest Pokémon on Ash's team, Phanpy's power makes up for his lack of experience.
Tailow
Treecko—Treecko is one of the elder Pokémon in Ash's Hoenn team. Always carrying a twig that it puts in its mouth, Treecko is a tough fighter, and often puts its integrity on the line in every battle.
Corphish—Corphish is a Pokémon caught on Dewford Island while Ash was training for his rematch with Brawly. Corphish is a Pokémon unaware of its own strength, and often unintentionally hurts people as a sign of affection. Corphish is also short-tempered, trying to instigate a fight when peaceful solutions exist.
Ash, in his Red persona, the player's character in Pokémon Red, Green, Blue, and Yellow. He is also a fightable trainer in the Pokémon Gold/Silver/Crystal games. He can only be faced after defeating the Kanto Gym Leaders in those games. Once that is done, the player must travel to Mount Silver to find him.
Ash's Japanese name, Satoshi, comes from the name of the creator of Pokémon, Satoshi Tajiri.
In one of the Pokémon manga series, Pokémon: The Electrical Adventures of Pikachu, Ash has a crush on May Oak (not to be confused with May (Haruka) from the anime), Gary Oak's sister.
