"Pokémon XY & Z" is the third season of the Pokémon XY series, continuing the adventures of Ash Ketchum and his companions in the Kalos region. The narrative builds on the events of the previous seasons, with Ash striving to earn Gym Badges to qualify for the Kalos League while deepening his bond with his Pokémon, particularly his Greninja, which undergoes a unique transformation known as Ash-Greninja. This transformation becomes a central focus, as it symbolizes the strong connection between Ash and Greninja, allowing them to synchronize their abilities in battle.

Serena, a childhood friend of Ash, continues her journey to become a Pokémon Performer, aiming to win Pokémon Showcases and earn the title of Kalos Queen. Her character development is highlighted as she refines her skills and strengthens her bond with her Pokémon, particularly her Braixen. Clemont, the Lumiose City Gym Leader, and his younger sister Bonnie accompany Ash and Serena, with Clemont focusing on his inventions and Bonnie forming a close relationship with the Mythical Pokémon Zygarde, which plays a pivotal role in the overarching plot.

The series introduces Team Flare, a villainous organization with a sinister plan involving Zygarde and the ultimate weapon. Lysandre, the leader of Team Flare, seeks to reshape the world by harnessing Zygarde's power, leading to a climactic confrontation. The narrative intensifies as Ash and his friends uncover Team Flare's schemes, culminating in a large-scale battle to protect the Kalos region. The involvement of Zygarde, particularly its Core form, which Bonnie names Squishy, adds depth to the storyline, intertwining the personal journeys of the characters with the larger conflict.

Throughout the series, Ash competes in the Kalos League, facing formidable opponents and showcasing his growth as a Trainer. The battles are dynamic and strategic, emphasizing the synergy between Ash and his Pokémon. The season concludes with the resolution of the Team Flare arc and the Kalos League, leaving a lasting impact on the characters and their relationships. The narrative balances personal growth, friendship, and high-stakes action, making it a significant chapter in the Pokémon anime series.