Quagsire is a light blue, bipedal, amphibious Pokémon. Its head is broad and round, having little neck to distinguish it from the rest of its body. It has a wide mouth and tiny, black eyes. A wavy, purple stripe runs down its back. Along its spine is a dark blue fin, which is larger on the male than on the female. Quagsire's hands and feet both have three digits. Its outer layer of skin is slimy and slippery. Quagsire is seemingly related to Clodsire.
Quagsire is carefree and sluggish by nature, although it is protective towards Wooper. An unintelligent Pokémon, it tends to bump its head inadvertently while swimming and seems not to care. It hunts for food by leaving its mouth wide open in water and waiting for its unaware prey to blunder in. Because Quagsire does not move, it does not get very hungry and can afford to wait for its food. Quagsire lives in clean bodies of freshwater, as well as muddy swamps. During the day, Quagsire avoids sunlight by submerging itself in the water.
In the anime, wild Quagsire are shown to have an annual celebration at Blue Moon Falls when the moon is full. There they attempt to shoot round objects they have collected to the top of a waterfall with their attacks, to see who can launch their objects the highest, with the apparent target being the moon.
Quagsire debuted in Once in a Blue Moon, where one of them stole the GS Ball from Ash for a festival that more Quagsire attended.
In Training Wrecks, Rocky used a Quagsire in his battle against Ash. It went up against Pikachu and Grovyle, alongside a Walrein. Before Pikachu could hit Walrein with its Electric attacks, Quagsire would protect Walrein from being shocked, due to its immunity to electricity, while Walrein's Ice Ball hit Grovyle and Pikachu hard. However, after the Ice Ball went slower every turn, Pikachu and Grovyle defeated Walrein and Quagsire.
In Like It Or Lup It!, a Quagsire was part of a gang of Water-types.
In A Crasher Course in Power!, Crasher Wake used a Quagsire in his Gym battle against Ash. It battled and defeated Turtwig before losing to Buizel and his Ice Aqua Jet attack. Quagsire reappeared briefly in Mamie's flashback in For The Love Of Meowth.
In A Faux Oak Finish!, six Quagsire kidnapped Professor Oak as he was making a poem about two of them. They then brought him to a Lombre that wanted to evolve.
In Defending the Homeland! and Beyond the Rainbow!, multiple Quagsire were living in the wetlands where Ash's Goodra came from. They then made further appearances in Pokémon the Series: XY.
In Tricks of the Trade, a Quagsire was at the Pokémon Swap Meet in Palmpona.
In The Fire-ing Squad!, nine Quagsire competed as a team in the Fire and Rescue Grand Prix.
A Quagsire appeared in a flashback in No Big Woop!.
A Quagsire appeared in a fantasy in The Totodile Duel.
At the end of Love, Totodile Style, Ash's Totodile fell in love with a Quagsire.
In Spell of the Unown: Entei, Lisa used a Quagsire to battle Pikachu. The match ended in a draw after Pikachu headbutted Quagsire and both Pokémon fainted.
In The Wayward Wobbuffet, a Quagsire was swimming in a river when it encountered Jessie's Wobbuffet, which got lost, and gave it directions.
In Ring Masters, a Quagsire competed in Rikishii Town's Sumo Conference.
A Quagsire appeared in Celebi: The Voice of the Forest.
In Got Miltank?, three Quagsire were living at the Pokémon-exclusive oasis.
In Dueling Heroes, a Trainer's Quagsire competed in the Whirl Cup.
In Bulbasaur... the Ambassador!, a Quagsire was among the feuding Pokémon at Professor Oak's Laboratory.
In The Legend of Thunder!, a Quagsire was at the Pokémon Center.
Multiple Quagsire appeared in Pokémon Heroes: Latios & Latias, with one under the ownership of a Trainer competing in the Tour de Alto Mare and the rest being wild.
A Trainer's Quagsire appeared in You're a Star, Larvitar!.
A Quagsire appeared in PK13.
A Quagsire appeared in the opening sequence of Lucario and the Mystery of Mew.
In On Olden Pond, a Quagsire was living in the lake.
A Coordinator's Quagsire appeared in Harley Rides Again.
A Quagsire appeared in Dawn Of A New Era!.
A Quagsire appeared in Drifloon On the Wind!.
A Quagsire appeared in The Rise of Darkrai.
In PK18, two Quagsire were on some rocks in the middle of a river.
A Quagsire appeared in Journey to the Unown!.
In PK20, multiple Quagsire were playing with a ball with a group of Wooper.
A Quagsire appeared in Bagged Then Tagged!.
A Quagsire appeared in Sticking With Who You Know!, under the ownership of Professor Kodama.
A Quagsire appeared in Zoroark: Master of Illusions.
A Quagsire appeared in Volcanion and the Mechanical Marvel.
In Deceiving Appearances!, five Quagsire were at Aether Paradise. One of them reappeared in a video in A Masked Warning!. Another reappeared in Don't Ignore the Small Stufful!.
Multiple Quagsire appeared in The Power of Us, with some under the ownership of different Trainers and one being wild.
A Trainer's Quagsire appeared in Restore and Renew!.
In On Land, In the Sea, and to the Future!, a Trainer's Quagsire competed in the Marine Athletic Race.
In JN139, a Quagsire appeared in a fantasy.
||Quagsire, the Water Fish Pokémon. The Quagsire makes its home in clean freshwater lakes. The Quagsire is covered by a slippery layer of skin, making this Pokémon especially difficult to handle.
||Quagsire, the Water Fish Pokémon and the evolved form of Wooper. Known as quite dim-witted, it doesn't care when it crashes its head against rocks or the bottoms of boats.
||Quagsire, the Water Fish Pokémon. Quagsire has an easy-going nature, and it doesn't care if it bumps its head on boats and boulders while swimming.