Slaking first appeared when it was defeating a trainer's Medicham during Malva's video.
Slaking was later Sawyer's first chosen Pokémon in his six on six Full Battle against Ash in the Lumiose Conference. It was up against Ash's Hawlucha, who used Karate Chop, High Jump Kick and X-Scissor. However, Slaking simply laid around and used Slack Off. Hawlucha repeated its attacks and went to use Flying Press, but just then, Slaking used Counter, which defeated Hawlucha with a single blow. It went up against Talonflame who used Steel Wing. While Slaking got hurt, it used Slack Off once more and healed itself. Sawyer first had Slaking counter Talonflame's Flame Charge with Hammer Arm, but the Lazy Pokémon lost its footing, got hit by Talonflame's attack, got struck by its Brave Bird and was beaten.
While coming back to Pallet Town, Ash recalled his battle at the Kalos League against Sawyer and his Pokémon.