Ash’s first Kalos Gym Badge in Pokémon the Series: XY is the Bug Badge. He earns it by defeating Viola, the Gym Leader of Santalune City, in a two-on-two battle.
Viola specializes in Bug-type Pokémon and uses Surskit and Vivillon. Ash’s first attempt at the Santalune Gym ends in defeat, largely because Viola’s strategy and the battlefield’s reflective surfaces make it difficult for Pikachu and Fletchling to respond. Ash studies the battle and returns with a better plan.
In the rematch, Ash defeats Viola and receives the Bug Badge. This victory begins his official Kalos Gym Badge collection and sets up the larger Kalos League storyline. Ash later collects seven more Kalos Badges before challenging the Kalos League.
The Bug Badge is not the same as the Boulder Badge, which Brock awards in Pewter City during Ash’s Kanto journey. Badge names vary by region, and the Kalos series uses a different Gym and badge system from the original Kanto arc.