From Bulbapedia, the community-driven Pokémon encyclopedia.
Ash's hat (Japanese: サトシのぼうし Satoshi's hat) is the most important and famous item of clothing that Ash Ketchum is seldom seen without. Throughout the Pokémon anime, Ash has worn five different hats so far, one for each of the five different series.
Pokémon League Expo hat
Ash wearing his Pokémon League Expo hat backwards
Ash's first hat, worn during the original series, was easily the most well-known of them: an official Pokémon League Expo hat that was red and white with a green, stylized "L" on the front, which Ash claimed to have "sent in about a million postcards" in order to obtain. Misty seems to have tried to win it as well, as she stated she sent in a postcard. Ash wore this hat during his journey through Kanto, the Orange Archipelago, and Johto, and was very attached to it, becoming enraged when a Mankey stole it and played keep-away with it in Primeape Goes Bananas.
Commonly, Ash would turn the cap backwards, particularly when he was concentrating heavily, such as when he would face a Trainer or capture a Pokémon. This was seen most often early in his journey in Kanto, gradually becoming less frequent until his journey in Johto ended, by which time he hardly ever turned his cap.
Advanced Generation hat
Ash's Advanced Generation hat
Ash wearing his AG hat backwards
After returning from Johto, Ash was given a change of clothes by his mother, and he immediately changed into them, including switching his old hat for a new black-and-red one which had a green Poké Ball symbol on it. He seemed to have no hesitation in changing hats, despite the attachment shown in Primeape Goes Bananas.
Like the first one, his second hat was also stolen by a monkey-like Pokémon which Ash later captured, this time an Aipom in Slaking Kong!. In a surprising display of maturity, however, Ash did not climb any trees or scream at Aipom when his hat was stolen. Instead, he actually accepted that it was gone (or so he assumed), saying that he would "feel strange" without it. At the end of the episode, Aipom returned Ash's hat to him. However, Aipom followed Ash and his friends to the Kanto Grand Festival where it stole his hat again. After Ash captured her, Aipom stole Ash's hat multiple more times as the Advanced Generation series ended and the Diamond & Pearl series began.
Ash rarely flipped his hat during the series. Occasions on which he flipped his hat include when he was dressed as an eggplant in Claydol Big and Tall, when he was cleaning the dojo in Pasta La Vista!, and during the climax of the ninth Pokémon movie.
Diamond & Pearl hat
Ash wearing his DP hat backwards
Ash's Diamond & Pearl hat
Ash had received his third hat in a package from his mother while in the Sinnoh region. Though his clothes changed quite a bit between their Advanced Generation and Diamond & Pearl iterations, his hat remained similar; though while his second hat had a green Poké Ball symbol, his third one was blue. This hat also had a larger and square black area around the Poké Ball, while the black area in the Advanced Generation series was spherical.
Ash flipped this hat only twice: in his battle against Tobias in The Semi-Final Frontier! and briefly in the thirteenth Pokémon movie.
Best Wishes hat
Ash wearing his BW hat backwards
In the Best Wishes series, Ash wore a red and off-white hat. Unlike the hats seen during the Advanced Generation and Diamond & Pearl series, this hat bore a slight resemblance to the one seen in the original series, but with a blue Poké Ball design for a logo and no line running down the middle.
In Dancing With the Ducklett Trio!, Ash's hat was stolen for the third time, this time by a trio of Ducklett.
During the early episodes of the Best Wishes series, Ash flipped his hat somewhat often, with decreasing frequency as the series went on. This is the same pattern seen in the original series with the Pokémon League Expo hat.
A comparison of the similarities between Ash's hat from the original series (left) to the Best Wishes series (right)
Ash wearing his XY hat backwards
In the XY series, Ash wears a red hat with a white brim and a white semicircle across the front. This hat resembles the hat worn by Red in the games from Pokémon FireRed and LeafGreen onwards.
Ash has flipped his hat once so far in this series, when he caught Fletchling in XY003. Ash has also had the tendency of adjusting his hat a lot in this series; this has been seen more commonly than seeing him flipping his hat backwards.
In the games
His hat in Hey You, Pikachu
- In Hey You, Pikachu!, the original hat, along with the rest of the outfit, can be seen hanging on a coat rack in the player's bedroom. Pikachu uses the hat in "The Piñata Game" to cover his eyes.
All of Ash's hats have been produced for people to wear. Ash's Advanced Generation hat was available to purchase at PokémonCenter.com before it shut down. His hats can be found at numerous stores (including the Pokémon Centers in Japan) and on online auction sites such as eBay.