Rhyanna's Misdreavus had a Pokemon battle with her younger brother in which it defeated his Murkrow fairly easily. He didn't like the fact that he was defeated so easily and got mad at his sister.
With the help of her Misdreavus, Brock found the Dusk Stone under a large rock but Team Rocket showed up and tried to take the Dusk Stone.
Misdreavus was captured with Meowth's net which shocked it when it tried to get away. Brock's Sudowoodo was unable to defeat the large mecha and it captured Lucile, Misdreavus and the Dusk Stone. It wasn't until Mitchell arrived that it was rescued.