Tobias first appeared in League Unleashed!. In Casting a Paul on Barry!, while Ash and Barry were looking up information about their next League opponents, Conway told them that Tobias managed to easily obtain his eight Gym Badges and advance through the first two rounds of the Lily of the Valley Conference using just his Darkrai.
In Working on a Right Move!, Tobias appeared unshadowed for the first time, and he was shown to have advanced into the Top 8. In Battling a Thaw in Relations!, it was shown that he had advanced yet again, now placing in the Top 4 of the Lily of the Valley Conference. In The Semi-Final Frontier!, he battled against Ash's Sceptile who managed to overcome Darkrai's attacks and defeat it. Tobias then called out his Latios, who managed to defeat the remainder of Ash's team (while fainting itself), winning the match for Tobias.
Later, Tobias defeated his final round opponent with just his Darkrai, thus winning the Lily of the Valley Conference.