Calem is a young boy who lives in Vaniville Town when the protagonist moves into town. Calem is the main rival of the character, choosing the starter Pokémon which is super-effective to the player's. He is also the character who teaches the player and Shauna how to catch a Pokémon, catching a Bunnelby with the use of his Fletchling. Soon after, he can be seen in Santalune Forest with the other friends.
Calem is the child of two prominent Pokémon battlers, and is seen as one of the two best battlers of the group of friends, alongside the protagonist.
The next time Calem battles the player is in front of the Coumarine Gym.
When the group of friends meets up and decides to go to the haunted area in Route 14, Calem is the only one of the friends to not go to the house, claiming that he has to train. He then helps the player defeat Team Flare at the Poké Ball Factory.
The next time Calem battles the player is in front of the Anistar Gym. After the player defeats the gym, he will ask for a rematch, but cancels his challenge after Lysandre announces his plan of eradicating all life forms not a part of Team Flare. He then helps the player defeat Team Flare get to the legendary Pokémon and defeat Team Flare for good.