From Bulbapedia, the community-driven Pokémon encyclopedia.
Hikari's Pochama (Japanese: ヒカリのポッチャマ Hikari's Pochama) is Hikari's first Pokémon. She befriended it after saving it from an Ariados's attack, when Pochama and Chimchar had fled from Professor Rowan's lab. She also fed Pochama before receiving it from Rowan. It is voiced by 小桜エツ子Etsuko Kozakura.
Pochama initially would not accept food from Hikari - as described in the Pokédex, Pochama have high pride and dislike receiving food from people; however, it seems to have a large appetite for Pokémon food and does not like having any taken away from it. It shows signs of having a short temper, getting into disagreements with other Pokémon and its trainer.
For more information on this species of Pokémon, see Pochama.