Azumarill is a blue, bipedal semiaquatic leporine Pokémon that has an ovoid body. The lower half of its body is white with a white, bubble-like pattern above it, which helps to camouflage it in water. It has elongated, rabbit-like ears with red insides and circular eyes. When in the water, it rolls up its ears to prevent the insides from becoming wet. Its arms and feet are short with rounded ends and no discernible digits. It has a black zigzagging tail with a blue, bubble-like tip. The tip of its tail tends to glow when it attacks or is excited.
Azumarill has highly developed hearing that allows it to hear distances, even when it is underwater. By keeping still and listening closely, it can identity prey even in wild, fast-moving rivers. If Azumarill spots a drowning Pokémon, it will make a balloon out of air that helps them breathe or when Azurill are playing near the rivers. It lives in rivers and lakes, and can live in the water all day long.
In Love, Totodile Style, Trixie uses an Azumarill in her circus. She became the target of Team Rocket and the love interest of both Ash's Totodile and Trixie's Golduck, though it reciprocated the feelings of only the latter.
An Azumarill is a friend of the Pichu Brothers. It appeared in Trouble in Big Town, Of Meowth and Pokémon (Part 1), Big Meowth, Little Dreams, Pichu Bros. in Party Panic, and Giratina and the Sky Warrior.
In Tie One On!, Jackson's Azumarill first got into an altercation with Ash's Pokémon over possession of an apple. It then battled Ash during the Silver Conference, going up against Pikachu and being defeated by Thunder.
In PK13, an Azumarill was about to perform a song in the Summer Festival when a wild Skarmory kidnapped it.
In Shapes of Things to Come, Paul used an Azumarill during his Gym battle against Roark. It went up against Roark's Geodude and lost to its Rollout despite having the type advantage. In the next episode, Azumarill was revealed to have been given to a passing Trainer.
In The Pirates of Decolore!, an Azumarill was a powerful and eager member of Croconaw's pirate gang. It had no problems with stealing food from humans. It battled Ash's Snivy and Pignite with Croconaw but was defeated. However, it assisted in the rescue of the Darumaka before joining Officer Jenny.
In Trial on a Golden Scale!, an Azumarill appeared under the ownership of Danika.
In The Heartbreak of Brock, an Azumarill lived at Temacu's father's lab.
In The Big Balloon Blow-Up, a Trainer's Azumarill watched the Pokémon Balloon Race.
In Dueling Heroes, a Trainer's Azumarill competed in the Whirl Cup.
In The Legend of Thunder!, an Azumarill was at the Pokémon Center.
In Pokémon Heroes: Latios & Latias, a Trainer's Azumarill competed in the Tour de Alto Mare.
An Azumarill appeared in A Ruin with a View.
In Lights, Camerupt, Action!, an Azumarill was a supporting actor in the Western movie Brock reminisced about.
A Coordinator's Azumarill appeared in Mean With Envy.
In On Olden Pond, an Azumarill was living in the lake.
In Off the Unbeaten Path, a Trainer's Azumarill participated in the Pokémon Orienteering competition.
A Coordinator's Azumarill appeared in What I Did for Love!.
In the beginning of Pokémon Ranger and the Temple of the Sea, an Azumarill and its pre-evolved forms put out a forest fire while under the control of Solana's Capture Styler.
In Arrival of a Rival!, a Coordinator's Azumarill competed in the Jubilife City Pokémon Contest.
An Azumarill appeared in The Rise of Darkrai.
In One Team, Two Team, Red Team, Blue Team!, a student used an Azumarill provided by the Pokémon Summer Academy for the second leg of the Pokémon Triathlon.
An Azumarill appeared in To Thine Own Pokémon Be True!.
In An Old Family Blend!, a Trainer's Azumarill competed in the Lily of the Valley Conference.
An Azumarill appeared in Zoroark: Master of Illusions.
An Azumarill appeared in Mewtwo — Prologue to Awakening.
Two Azumarill appeared in Kalos, Where Dreams and Adventures Begin!.
An Azumarill appeared in Lumiose City Pursuit!.
A Trainer's Azumarill appeared in Mega Evolution Special III.
An Azumarill appeared in A Fashionable Battle!, under the ownership of a Furisode Girl.
An Azumarill appeared in Hoopa — The Mischief Pokémon.
In Pikachu and the Pokémon Music Squad, three Azumarill were living in the forest.
A Trainer's Azumarill appeared in A Performance Pop Quiz!.
An Azumarill appeared in Volcanion and the Mechanical Marvel.
Six Trainers' Azumarill appeared in The Power of Us.
In Battling on the Wing!, a Trainer's Azumarill watched the battles of the Manalo Conference.
A Trainer's Azumarill appeared in Secrets of the Jungle.
||Azumarill, the Aqua Rabbit Pokémon. The evolved form of Marill. This Pokémon uses its large, highly developed ears to hear great distances, even underwater.
||Azumarill, the Aqua Rabbit Pokémon. Azumarill lives in rivers and lakes, and while in water, its body color and pattern confuses its enemies.
Azumarill may be based on a combination of a rabbit and a beach ball or possibly a personal flotation device or lifebuoy. It could be also possibly based on the swamp rabbits, which have a strong preference for wet areas (such as cypress swamps, marshes, floodplains, and river tributaries) and that will take to the water and swim. Azumarill's water-like splash pattern may reflect from the camouflage of countershading of aquatic animals such as sharks and penguins, being that they have a dark coloration on top to match the dark water underneath and a white coloration on their under to match the sunlight from above. Its body shape and body pattern could be a reference to Easter eggs.
Azumarill may be a combination of azure (a shade of blue), azul (Spanish and Portuguese for blue), or azul marino (Spanish for navy blue), mar (Spanish and Portuguese for sea) or Marill, and possibly rill (a small river or brook).
Marilli may be a combination of 丸い marui (round or circular) or 鞠 mari (ball), 瑠璃 ruri (lapis lazuli), and possibly rill (a small river or brook) and マリンブルー marine blue.