Anipoke
Hassel appeared in the Pokémon anime for the first time in spring 2024, at the beginning of the "Terastal Debut" arc which is known as season 2 in the western dub.
HZ046 - How Thrilling! Orange Academy (Welcome to Naranja Academy)
Led by Nemona, Liko and the others are visiting the Naranja Academy. They meet Hassel, who introduces himself as the school's art teacher. He is interrupted by Rika and they have a small argument with each other in the background while Dot tells Liko and Roy that Hassel and Rika are part of the Elite Four (they're famous!). Later Hassel watches Liko and Anne's battle along with the rest of the Elite Four and Geeta.
HZ048 - Shine! The Brilliance of Fire and Art (Sparkle! The Glow of Flame and Art)
Liko, Roy and Dot meet Hassel at Artazon Town, where he is helping to arrange an art festival. He leads the gang to meet gym leader Brassius as Roy needs to battle him for his Terastal test. Upon meeting Brassius, the kids find out that Hassel and Brassius are good friends and Brassius tells them how Hassel saved him from a bad art slump, which of course is the same backstory they had in the games. It also turns out that Brassius and Hassel are friends with Liko's father Alex, who is also an artist.
HZ055 - Showdown! The Big Four of Paldea (Showdown! The Paldea Elite Four)
In the second half of the episode, Roy and Brassius have a friendly battle against Hassel in a tournament meant for those who have completed their Tera training tests. Hassel uses Flapple and Baxcalibur against them, and wins.
HZ067 - Shine, Terastal! Liko VS Roy!! (Shine on, Terastallization! Liko vs. Roy!)
Hassel and Brassius are among the audience watching Liko and Roy's battle. He tearfully compliments them for the wonderful battle later that evening.
HZ079 - Over the Top
Hassel serves as the battle referee as Liko, Roy and Dot battle against Geeta. Among others, he is impressed by the strength and growth of the three kids.
HZ096 - Clash! The Dragon Rampage Gang (Crash! Team Dragon Rampage!)
There is only a brief mention of Hassel in this episode, accompanied by a cute image of him. Dot tells the others that Hassel is a Dragon tamer as they are discussing the Dragon tamer clan at Blackthorn City.
HZ0116 - Training Begins! Terarium Dome
While Hassel doesn't appear in this episode at all, the characters mention him quite a few times. As we know from the game, Hassel knows Drayton and his grandfather, and this episode elaborates that Hassel and Drayden are indeed friends. Drayton also implies that he does have respect for Hassel and is impressed that Roy studied under him.
HZ0127 - Hyper Training! Everyone's Respective Feelings
Hassel offers to be Ult's battle opponent, whom he meets for the first time. Upon meeting Ult and his Dragonite, Hassel regonizes both of them. It is left unclear where he exactly knows them from, though. (A later episode reveals that Ult's father and his Dragonite are a rather famous duo among Dragon tamers.) Hassel wins against Ult easily with his Baxcalibur, and offers him some advice.
HZ0131 - Come On! Gather Up! Our Fellow Companions
Along with other staff of the Academy, Hassel is briefly seen watching the Rising Volt Tacklers' airship fly by the school.