Wallace first appeared in Our Cup Runneth Over!. He was first seen on the Sinnoh Now television program when the crew advertised the Wallace Cuptaking place in Lake Valor. Ash and his friends were looking for Wallace and found him relaxing near a lake with his Milotic. Even though Wallace had his day off from his busy schedule, he allowed the group to stay. Wallace had Dawn show off her Contest moves to him. She did so by having a practiceContest Battle with Ash. He praised the two for their match while Brock explained that Buizel used to belong to Dawn and he was traded to Ash in exchange for Aipom. After watching Ash and Dawn's practice match against each other, he asked Ash to enter the Wallace Cup with his Buizel.
Team Rocket show up in their disguises. Despite having more company, he did a practice appeal with his Milotic for them to prove what relaxing and playing with Pokémon can do during his time off. When Milotic finished with Twister, Wallace left in a wave formed by the appeal. Wallace was then seen on TV being interviewed by Marian.
It was mentioned in his debut episode that, like in the games, Wallace is the former Sootopolis City Gym Leader who eventually moved up to the position ofChampion of the Hoenn League. He is also an accomplished Pokémon Coordinator, having won the Grand Festival with his Milotic. For his achievements in the contest world, he was labeled as a Contest Master (Japanese: コンテストマスター Contest Master).
In Staging a Heroes' Welcome!, during the beginning of the Wallace Cup, Wallace made a speech on stage and held out the audience and participants the Aqua Ribbon. He concluded the speech by having Milotic perform as part of his appearance. Wallace then acted as a judge for the Performance Stage of the Pokémon Contest.
In Pruning a Passel of Pals!, Wallace welcomed back the participants as the Wallace Cup was resumed. He judged the battles of the battle round, including the one with Ash and Kyle.
Wallace continued acting as judge for the battle round in Strategy With a Smile!. When May and Dawn were in the finals and were about to begin their battle, Wallace gave some encouraging words to the two. After Dawn was able to defeat May and win the Contest, Wallace awarded Dawn the Aqua Ribbon. Wallace then closed the Wallace Cup by having Milotic use Hydro Pump in the air.
It was revealed in Battling the Generation Gap! that the Pokémon Stylist Lila designed the outfit he used in the Top Coordinator Carnival.
He made a brief cameo in SS024 in Dawn's dream.
In Goodbye, Junior Cup - Hello Adventure!, Wallace made another cameo when he was mentioned by Dawn to Ash, Iris and Cilan.
In Mega Evolution Special II, he was implied to have lost his Champion title to Steven, who was stated to be Hoenn Champion in that episode.