Formerly, Wallace was the Gym Leader of Sootopolis City in Hoenn. At some point, later, he defeated Steven, then-Champion of Hoenn, and took his place. Even as Champion, Wallace continued his career as a Coordinator, winning the Hoenn Grand Festival, and becoming the Top Coordinator. Rumor has it that he is also Top Coordinator in Sinnoh.
Wallace also owns both a male and female Jellicent. He calls them his "Double Battle Squad" due to his tendency to use them both in Double Battles at the same time. They have only been used in Contests, so far, however.
In Ruby and Sapphire, he runs Sootopolis City Gym where he gives out the Rain Badge as well as TM03 (Water Pulse). In Emerald, the storyline was revised so that he lost the gym to his mentor, and Wallace instead maintains a position as the Champion of the Elite Four. Steven, who was the Champion in the previous versions, is instead a legendary wandering Trainer.