Pocchama, also known as Piplup, presents a light-blue, penguin-like form insulated by thick down against cold. Its dark blue head showcases a primarily white face and a short, yellow beak. Dark blue feathers extend down its back and around its neck, creating a cape-like effect, while a small, light-blue crown-like marking sits above its beak. It possesses flipper-like arms and yellow feet, each with three toes.

This Pokémon exhibits a notably proud and self-assured demeanor, often striking confident poses—such as puffing out its chest after an occasional stumble caused by its somewhat unsteady walking. Despite this terrestrial clumsiness, it excels as a skilled swimmer, capable of diving for over ten minutes to hunt. Animated portrayals have also shown it flying short distances.

Accompanying its trainer and companions to Michina Town, Pocchama nearly gets swept into a spatial distortion vortex alongside Pikachu during a lakeside encounter, requiring rescue by Dialga. Later, it partners with Pikachu in a tag battle against local trainers' Heracross and Beautifly. Their coordinated efforts contribute to a victory, with the trainers sharing the resulting watermelons among all present Pokémon.

Throughout subsequent events—including Arceus's arrival and the temporal journey to rectify the historical betrayal involving the Jewel of Life—Pocchama remains present. Its role consistently aligns with supporting its trainer and the group during confrontations with legendary Pokémon and historical figures.