Following Gurkkin's advice, Ash & co. join Korrina on a trip to the Must Mountains to face a trainer who has experience with Mega Evolution. However, during the battle, Korrina's Mega Lucario loses control of its power again, causing it to lose. The elderly trainer decides to help Korrina and Lucario train and control their power, but through some of the more unrelated methods such as flower arranging. Will this help Korrina and Lucario overcome their problems?