Lost Leader Strategy! - S11.E14

In the forest just outside Veilstone City, the group witness a young female martial-artist and a Lucario in a fierce battle. The girl is revealed to be Maylene, the city's Gym Leader, at which point Ash immediately asks for a Gym Battle. However, she recently lost to Ash's rival Paul, and is depressed over her defeat. Further insight into the matter is revealed by Reggie, Paul's older brother. Reggie also helps Ash's Staravia learn Brave Bird.