Trip is one of Ash's rivals, his main one during the Unova region, along his journey.
While traveling to take on the Unova League, Trip takes photographs of Pokémon that he encounters and is also known as a Pokémon Photographer. Unlike Paul (Ash Ketchum's previous arch-rival), Trip does care for his Pokémon instead of consider them tools, but he prioritizes becoming a strong trainer, and obnoxious, like Gary Oak. The main reason he took a dislike to Ash is because of his training style and more outgoing personality, whereas Trip tended to mostly keep to himself.
He is not as narcissistic as Gary or as harsh as Paul, but he had a strong dislike towards Ash. However, before running into Alder, they were shown to have at least something resembling mutual respect.
Unlike Gary, who thought Ash wasn't good enough, and Paul, who outright hated Ash's guts at first, Trip saw Ash as an annoyance. Unlike the last two he was occasionally willing to help him out, such as when he showed him how Oshawott could not land Aqua Jet because its eyes were closed or when Scraggy's newly learned focus blast was not ready.
Trip is bound to learn that becoming the champion does not depend on just becoming strong. His goal was to become the next Pokémon Champion of the Unova region, but was defeated by Ash in the first round of the Unova League.
Trip is somewhat xenophobic, as he does not think very highly of the Kanto region — or anyone from there. He thinks of anyone from Kanto as a redneck from "the boonies" who should go back to the basics of Pokémon.
Like Paul, Trip lets his emotions betray him in his battle against Alder which results in him to easily loose against him.
Trip mellowed out considerably after his battle with Alder. Realizing that he was not a high-level trainer as he thought he was, he (mostly) ceased belittling people he saw as beneath him even towards Ash. When he left the Junior Cup, he expressed a genuine interest in battling Ash at the forthcoming Unova League. When he randomized as Ash's opponent in the Unova League, Trip says he is looking forward to battling Ash.
After losing to Ash at the league, he dropped any disdain he still had for Ash and they now consider each other friends. Like Paul, there is no reason for Trip to stay in the Unova League since he lost, when he declared to Ash that he won fair and square as well he decided to leave in his quest to defeat Alder one day.
