In the Diamond & Pearl series, Ash appeared with another new outfit, consisting of a black vest with a white collar and yellow stripe, a white short-sleeved undershirt, blue cargo jeans, black and red sneakers, and his hat's Poké Ball symbol is blue.
Ash's spiky hair is slightly shorter and slightly dull, and his lighting bolt-like markings are short and slightly big.
Since entering the Sinnoh region, Ash is less of a hot head when it came to Pokémon battles but kept it when Pokémon were being mistreated while still keeping his other traits. Also, Ash is more open up to advice and is more patient with others. Ash is beginning to be less cocky due to meeting a rival who only wanted to bring the power out of a Pokémon, Paul, and is beginning to take some of his rivals more seriously like he was for Gary while keeping his love for Pokémon. Ash is once again in a role of mentor for an another rookie trainer and coordinator named Dawn, much like he was for May.
When his Aipom join up with him and his Pikachu, Ash had to go get Aipom PokéBall from Professor Rowan. Whenever Ash and his friends encounter or call Professor Rowan he would greatly give them helpful advice or assistance whenever they need it. Ash with his friends attended the Pokémon summer academy that Professor Rowan runs.
Ash first meet Staraptor when he was a Starly as he instantly caught him as his first Pokémon from Sinnioh due to wanting to look for Pikachu from the air, after he got separated from him. They instantly became good friends with each other right away, after Ash caught Staraptor. When he evolved into Staravia and Staraptor, Ash had him battle in a couple of his gym battles and had him carrying smaller Pokémon on his back, especially Pikachu. Also, Ash was proud in Staraptor as he grew a lot stronger in his skills and abilities.
Although they weren't friends due to their beliefs of raising Pokémon, Ash and Paul could't ignore each other if they try due to being rivals. Ash try his hardest to get his respect from Paul due to seeing him as a weak trainer for bonding with Pokémon over training with strength and power. During their full battle in the Lilly of the Valley Conference, Ash greatly beat Paul and got respect from him, although he got some of it when he heard that he beat the Kanto Battle Frontier, which led them to form a small friendship.
Ash was able to hit of a friendship and friendly rivalry with Nando right away when they first meet. Also, Ash was impress how Nando does well in both Gym Battles and Pokémon Contests. Ash battled Nando when they first meet and in the Lilly of the Valley Conference where he won both times.
When Ash first meet Torterra during its time as a Turtwig was when it save Pikachu from Team Rocket. However, Torterra thought Ash was part of Team Rocket but he cleared the misunderstanding with it and they instantly became friends. Ash caught Torterra as his second Pokémon he obtained in Sinnioh. During their time together, Ash and Torterra relationship grew as they became very close with each other. When it evolved into Grotle, Ash helped it recuperate the loss of its speed and train it very hard to help it became stronger in hopes of getting some of it speed back which worked as it learn a move that got some of it back. Also during its time as a Grotle and when it evolved into its final evolution, Ash uses Torterra in a lot of battles with very strong trainers, although it lost every time but it was still good experience for it.
Ash first meet Conway during the Hearthome City Tag Battle tournament. Through Conway, Ash was able to find a Gym to get one of his badges to compete in the Sinnioh League. They meet again in the Pokémon Summer Academy and they also battle in the Lilly of the Valley Conference which he won.
When Ash first meet Infernape was when it was a Chimcar and belong to a different Trainer, Paul. After its original trainer abandon it for not meeting his expectation, Ash decided to take Infernape in which it accepted thus becoming the third Pokémon he caught in Sinnioh. Ash and Infernape formed a close bond with each other. Also, Ash would risk his safety to protect Infernape. Ash was able to help Infernape become stronger as he helped it control its Blaze ability during its evolution line. After gaining control of its blaze ability, Ash was very proud of Infernape. Ash had Infernape help in a lot of battles due to being of one of his ace battlers.
Buizel is one of Ash's Pokémon as he was his fourth Pokémon he obtained in Sinnoh. He was originally Dawn's Pokémon but was later traded to Ash for Aipom because Buizel preferred battles over contests. Ash and Buizel form a close friendship with each as they love to battle.
Ash first meet Gliscor while it was as a Gligar where it took a liking to him. Although they help it and its friends get back home, Ash saw that Gliscor came back as it wanted to join his side and he happily accepts its request as he captures it thus becoming the fifth Pokémon he obtained in Sinnoh. Although he has a good relationship with Gliscor, Ash sometimes gets annoyed with it sometimes due to it falling on him but only does it to show affection towards him and even does it before and after evolving.
Angie is friend of Ash that he met during his time in the Pokémon Summer Academy. Ash formed a rivalry and friendship with Angie, although she ended up gaining a crush on him which he didn't notice. Also, Ash would help Angie whenever she needed it and was willing to take the fall for a mistake she made.
Every time they see encounter each other Ash would end up bumping into Barry due to him running way to fast to not see where he was going. However, Ash and Barry are both rivals and good friends with each other. Although they battle each other, Ash and Barry never got the chance to battle in the Lilly of the Vally Conference due to the latter losing to Paul. Barry watch Ash's battle during his participation and after he got eliminated from the tournament and Ash has done the same for him which show how supportive they are to each other as friends.
Ash first encountered Gible where it was a wild Pokémon with Old Lady Wilma. After visiting it, Gible had started following Ash, presumably having an interest in the young trainer. Ash was later reunited with Gible who made himself known by biting on his head. Seeing that Gible wanted to join him, Ash accepted him as he became the sixth and last Pokémon he caught in Sinnioh.
Pokémon the Series: Diamond and Pearl
Departing for Sinnoh, Ash once again left his previous captures from the Hoenn Region at Professor Oak's laboratory, with the exception of his Aipom, who'd snuck along. After arriving in Sinnoh by boat and reuniting with Brock, he gained yet another new traveling companion in Dawn, a confident girl interested in following in her mother's footsteps as a Pokémon Coordinator. After receiving new clothes from his mother in the mail, Ash gained a new rival in a Trainer named Paul. Later in the season, Ash misses meeting Team Galactic due to moving on with his journey too soon. He won his first two Sinnoh Gym Badges: a Coal Badge from Roark and a Forest Badge from Gardenia. Ash encountered J, who temporarily kidnapped Pikachu by turning it into stone. Ash's first Sinnoh capture was a Starly which evolved into Staravia, and a Turtwig. His final Sinnoh acquisition came when he adopted Paul's Chimchar by the end of the season.
DP Battle Dimension
In this season, Ash continued battling and earning badges while Dawn continued to earn contest ribbons. They also encountered Team Galactic and tried to stop them from stealing the Adamant Orb. During this time, Ash earns his fifth Gym Badge. For most of the season, Ash had to wait for Gym Leader Fantina to return to her Gym in Hearthome City in order to challenge her. Ash reunited with May during the Wallace Cup, and took part as a coordinator once again, per Hoenn Pokémon League Champion/Contest Master Wallace's request. Late one night with Pikachu, he saw the spirit of Azelf rise out of the lake the contest was being held at. He tied with Maylene, but earned a Cobble Badge from her and defeated both Crasher Wake and Fantina for the Fen and Relic Badges. He also acquired a new rival in Barry, a somewhat clumsy boy who insists on fining people. Ash acquired a few more Pokémon during this season; at the suggestion of Zoey, he traded his Aipom for Dawn's Buizel, the only trade so far he hasn't reversed; his Turtwig evolved into Grotle; and he caught a Gligar which became a Gliscor.
DP Galactic Battles
Continuing his journey in Sinnoh, Ash managed to beat Byron, winning the Mine Badge and Candice, winning the Icicle Badge. After his victory over Candice at the Snowpoint Gym, Ash briefly reunited with Brandon from the Battle Pyramid back in Kanto's Battle Frontier and witnessed a full 6-on-6 battle between him and his rival Paul. It was then after that battle that it was Ash's turn for his full battle with Paul, which occurred at Lake Acuity. However, Ash was not victorious in his battle with Paul, even after Chimchar evolved into Monferno. Along the trip to Sunyshore City, Ash and his friends encounter International Policeman Looker, and were recruited to help stop the plans of Team Galactic as the three of them were chosen to share a bond with the three Lake Spirit Pokémon, during which Brock managed to find Uxie. Managing to find Team Galactic in the middle of creating a new universe with the captive Lake Trio controlling Palkia and Dialga, Ash, Dawn and Brock freed the trio and Team Galactic was arrested while their leader vanished into the collapsing new world, effectively disbanding Team Galactic. At the end of the season, Ash gives Gliscor to the Air Battle Master named McCann for some training and has caught himself a Gible which was learning Draco Meteor.
DP Sinnoh League Victors
After the Team Galactic incident, Ash entered the Sinnoh League after beating Volkner and earning the Beacon Badge. He also reunited with Jasmine from the Olivine Gym back in Johto before heading to Lily of the Valley. Taking a different approach in this League than he did in Hoenn, Ash combined his previous captures with his current Pokémon to form well-balanced teams of new and old. The Sinnoh League was one of the hardest and most intense Leagues he ever competed in, as he had rivals Paul and Barry to compete with, and a mysterious trainer who joined with the Legendary Pokémon Darkrai. He battled against most of his rivals, save for Barry, who battled Paul and lost, so Ash's next match was against Paul. The battle was intense as Paul showed Pokémon that he didn't normally use while Ash had reassembled his team of six from their earlier battle at Lake Acuity. The fight came down to Paul's Electivire and Ash's Infernape. Despite taking heavy damage, Infernape won the match for Ash with its ability Blaze. After defeating Paul, Ash faced an opponent other Trainers in the League dreaded to face as he was hard to defeat: the Trainer with the Darkrai, Tobias. After losing three of his Pokémon to it, Ash was able to defeat Tobias' Darkrai with Sceptile and even knocked out Tobias' Latios with Pikachu. However, as the rest of Ash's Pokémon had fainted, he lost the match and was eliminated. To this day, the Sinnoh League remains Ash's most impressive performance in a Pokémon League Tournament: he reached the Top 4 - the farthest he'd ever gotten in any Pokémon League - and was the only one of Tobias' opponents to defeat two of his Pokémon, let alone his Darkrai. After the Sinnoh League, Ash bide farewell to Dawn as she wished to continue entering contests, and also parted ways with Brock, his oldest friend and longest-running traveling companion, for the final time, as Brock now wished to become a Pokémon Doctor.
With Professor Oak
Pokémon League status
- Pokémon Dress-Up contest: Runner-up
- Hearthome City Tag Battle Competition: Winner with Paul
- Hearthome Collection Contest: Runner-up
- Pokémon Summer Academy Triathlon: Winner
- Sinnoh PokéRinger - Squallville: Winner
- Pokémon ping-pong tournament: Top 32
- Twinleaf Festival Battle tournament: Winner
- Sinnoh Pokéathlon Tournament: Runner-Up
- This is the first time Ash:
- Had more then one main rival during his journey.
- Compete in more then one, official, Pokémon Contest.
- Traded one of his Pokémon to a traveling companion, although this is the second time he traded a Pokémon as the first time was during his Kanto journey.
- Shown to have a unique ability, although it was shown in one of the Movies.
- Been captured by a villainous organization as a hostage for a Pokémon.
- Didn't battle a main rival at the Pokémon League.
- Achieved Top 4 in a Pokémon League.
- Ash's Sinnoh Team are the very first team to:
- Have two out of the three Starter Pokémon on a team.
- Have a member that was traded from somebody else.
- Have a member from a previous generation group before evolving into the teams generation group.
- Have more then one Ground-type on a team.
- Have a Dragon-type on a team.
- Have a fully evolved Fighting-type.
- Have gotten their Trainer to the Semi-finals in a Regional League alongside their Trainer's Starter Pokémon, although his previous teams had a hand in achieving this rank.
- Like both his Kanto team and his Johto team, Ash's Sinnoh team has a member or two with a gender difference.
- Ash's Sinnoh Team shares a few similarities with just his Kanto team:
- Both of them have a member that was abandoned by their original Trainers.
- Both of them have more then one -type on a team.
- Both of them have a fully evolved Normal-type, although that is also shared with his Hoenn team. -type and
- Both of their teams had one or two members be sent to be with somebody else to help it become stronger.
- They both have a fully evolved Fire-type Starter Pokémon.
- They both have a member or two not participated in a Gym battle, although that is also share with his Johto team.
- They both had a member return from their training with somebody else.
- Ash's Sinnoh team shares a few similarities with just his Johto team:
- They both have six members on their teams.
- They both have a fully evolve Ground-type.
- They both team up with past members for their Regional Leagues.
- Ash's Sinnoh team shares a couple similarities with his Hoenn team:
- They both have a fully evolved Grass-type Starter Pokémon.
- They both had all their members participate in a full battle, although that is also shared with the two Orange Island Pokémon.