Tedesco first appeared spying on the cruise ship Ash, Iris, and Cilan were traveling on, when Mrs. Ripple invited them to her room to see her jewel collection. After that, while everyone was either watching or participating in the Marine Cup Tournament held aboard the ship, he was walking in the ship's hallways to find Mrs. Ripple's room. Tedesco carefully noticed Ripple's room guard Watchog in front of a door, thus locating the room.
After Cilan accused Teaque to be the thief of Mrs. Ripple's jewel, the "Eye of Liepard", he finally showed up in front of everybody when Teaque attempted to attack the entire group involved in the investigation with his Vanillite's Blizzard. Tedesco stopped the attack by calling out his Growlithe and letting it use Flamethrower. It then defeated both Vanillite and Teaque using Fire Fang. Mrs. Ripple's Purrloin recovered the jewel and removed Teaque's disguise, revealing that he was a wanted criminal who Tedesco was on the lookout for. He presented himself as an International Police member when the ship captain asked him who he was. It is assumed that he then arrested Teaque off-screen.
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