Calem is a bit tall for his age and thin boy, and has straight, chin length black hair with gray eyes and wears a dark red hat with sunglasses. He also wears a blue track jacket with white stripes, navy blue slim fit pants, and black boots with blue laces. He carries around a black messenger bag with blue decals on it. He has a Mega Ring on his left wrist.
If Serena is the player character, Calem appears as an NPC, and does not wear a hat.
In the games
As the player
Calem is a teenage boy who lives in Vaniville Town with his mother, Grace, and his friends Tierno, Trevor, Shauna, and his next door neighbor Serena. The five of them form a bond almost instantaneously and they decide to go on their Pokémon adventures together.
When he is not selected by the player, he will appear as the player's rival. He will select the starter that is strong against the player's starter (Fennekin if the player chose Chespin, Froakie if the player chose Fennekin and Chespin if the player chose Froakie), while Shauna will chose the remaining starter.
In the anime
Calem appeared in Pokémon Generations, where he was seen battling AZ with his Charizard and his Chesnaught, but he was defeated.
In the manga
Calem's counterpart in Pokémon Adventures is X. When he was young, X won a Kalos Junior Tournament. However, the pressure of being a celebrity at a young age had its effect on him and he became a shut-in. Later, he decided to go on a journey with his friends, Y, Shauna, Tierno and Trevor after Xerneas and Yveltal went on a rampage on their hometown, Vaniville Town.
- Calem has a very close resemblance with Hilbert, the male protagonist from the Generation V games Pokemon Black & White.
- Ash Ketchum's outfit for traveling through the Kalos region is based on Calem's own starter outfit. Despite this Calem is one of the few male player characters to exist in the anime.