#0423 · Sinnoh · Generation 4

Gastrodon

Sea Slug Pokémon · Water/Ground-type

Gastrodon is a Water/Ground-type Pokémon, the Sea Slug Pokémon, number 423 (#0423) in the National Pokédex. It was introduced in Generation 4 and comes from the Sinnoh region. It is 0.9 m tall and weighs 29.9 kg.

Gastrodon, the Sea Slug Pokémon, is a Water and Ground type with a soft, boneless body that grows back within hours if parts are bitten off. Its West Sea and East Sea forms, the Legends: Arceus Pokédex says, always fight fiercely when they meet.

How to pronounce Gastrodon

Gastrodon is pronounced GAS-truh-don. The capital letters show the stressed syllable.

Listen to Gastrodon said out loud:

In Japanese it is トリトドン (Tritodon).

Hear every other name on the Pokémon pronunciation guide.

Lore

Biology

Gastrodon measures 0.9 m and weighs 29.9 kg. It has six stubby legs, a yellow-edged mantle and a mark on its forehead that looks like a third eye. Pokédex entries say it once had a sturdy shell, and only a thin, hard plate is left.

Behaviour

When a natural enemy attacks, Gastrodon oozes purple fluid and escapes, and the Sword entry says it leaves a sticky trail of slime on land.

Habitat

The Pokédex says it lives in shallow tidal pools and on calm beaches. In Scarlet and Violet, West Sea Gastrodon lives at Casseroya Lake and East Sea Gastrodon in Areas One and Three of North Province.

Diet

The Legends: Arceus entry says it eats beach sand, and the Violet entry says it melts its prey with mucus before slurping it up.

Powers

Its Water and Ground typing makes it immune to Electric moves but 4 times weak to Grass. Storm Drain absorbs Water moves, and Sand Force is hidden. It learns Muddy Water, Earth Power and Recover, and with base HP 111 and Special Attack 92 it is a bulky special attacker.

Name origin

Gastrodon may combine 'gastropod' with don, Spanish for 'lord'. The Japanese name is Tritodon (トリトドン), which may combine Tritoniidae, a sea slug family, with the same don, and could also nod to the Spanish torito, 'little bull'.

Design inspiration

Gastrodon is a sea slug at heart. Bulbapedia suggests that the Scarlet and Violet entries, which say West Sea Gastrodon is declining and East Sea Gastrodon increasing, may be an inverse of real sea slug populations under climate change, where warm-water species become more common; this is a fan reading.

Evolution notes

Gastrodon evolves from Shellos at level 30 and keeps its form.

In the games

Champion Cynthia uses a West Sea Gastrodon at level 60 in Diamond and Pearl, where it first appeared, and again in Brilliant Diamond and Shining Pearl. It cannot be obtained in Legends: Z-A.

In the anime

Cynthia's Gastrodon, a West Sea one, first appeared in 'Double Team Turnover!' and beat Aaron's Beautifly and Drapion in 'Aiding the Enemy!'. Zoey's Shellos turned out to have evolved into Gastrodon at the Sinnoh Grand Festival.

Fun facts

• Gastrodon was featured alongside the bovine Pokémon Tauros, Miltank and Bouffalant in promotional artwork for New Year 2021, the Year of the Ox.
• Even east of Mount Coronet, no Trainer in Diamond and Pearl battles with an East Sea Gastrodon.
• Only East Sea Gastrodon appears in the wild in Alola and Galar, which Bulbapedia takes as a hint that those regions lie east of Sinnoh and Paldea.

Sources: Bulbapedia: Gastrodon (Pokémon) · Bulbapedia: Cynthia · Serebii: Gastrodon (Scarlet/Violet Pokédex)

Base stats

• HP: 111
• Attack: 83
• Defense: 68
• Sp. Atk: 92
• Sp. Def: 82
• Speed: 39

Gastrodon’s base stat total is 475. Its highest stat is HP.

Type matchups

What is Gastrodon weak to?

Gastrodon takes extra damage from Grass (4×) moves.

It resists Fire (½×), Poison (½×), Rock (½×), Steel (½×).

It is immune to Electric moves.

Evolution

What does Gastrodon evolve from?

Gastrodon evolves from Shellos at level 30.

Gastrodon is the final stage of its evolution family.

The whole family: Shellos, Gastrodon.

Abilities

• Sticky Hold: Prevents a held item from being removed by other Pokémon.
• Storm Drain: Redirects single-target Water moves to this Pokémon where possible. Absorbs Water moves, raising Special Attack one stage.
• Sand Force (hidden ability): Strengthens Rock, Ground, and Steel moves to 1.3× their power during a sandstorm. Protects against sandstorm damage.

Moves

Moves Gastrodon learns by level up in Scarlet / Violet

TM moves (47)

Gastrodon can learn 47 moves from TMs in Scarlet / Violet: Take Down, Mud-Slap, Protect, Water Pulse, Chilling Water, Facade, Bulldoze, Icy Wind, Mud Shot, Rock Tomb, Endure, Rain Dance, Sandstorm, Snowscape, Dig, Body Slam, Sleep Talk, Rock Blast, Waterfall, Stomping Tantrum, Rest, Rock Slide, Spikes, Substitute, Liquidation, Stealth Rock, Surf, Amnesia, Helping Hand, Earth Power, Ice Beam, Hydro Pump, Blizzard, Sludge Bomb, Earthquake, Stone Edge, Giga Impact, Hyper Beam, Tera Blast, Sand Tomb, Weather Ball, Pain Split, Whirlpool, Muddy Water, Sludge Wave, Skitter Smack, Curse.

Egg moves (11), which Shellos can hatch knowing:Acid Armor, Clear Smog, Counter, Curse, Mirror Coat, Mist, Sludge, Spit Up, Stockpile, Swallow, Yawn.

Breeding & training

• Gender: 50% male, 50% female.
• Egg groups: Water 1, Amorphous.
• Egg cycles: 20 (steps to hatch, Scarlet/Violet: 2,560).
• Catch rate: 75 out of 255.
• Base friendship (Gen 8 onward): 50.
• Growth rate: Medium (1,000,000 experience points to reach level 100).
• Defeating it gives 2 HP effort values.
• Base experience yield: 166.

Pokédex entries

Eats beach sand for nourishment. Should one Gastrodon encounter another of a different color, a fierce battle will inevitably ensue. (Legends: Arceus)

The softness of its body helps disperse the force of impacts, so although its body is uncommonly squishy, it's also surprisingly resilient. (Shield)

Its search for food sometimes leads it onto land, where it leaves behind a sticky trail of slime as it passes through. (Sword)

Their shape and color change, depending on their environment and diet. There are many of them at beaches where the waves are calm. (Ultra Moon)

Long ago, it had a shell on its back. There's now a vestigial plate on its back that's hard but thin. (Ultra Sun)

Plankton, invisible to the naked eye, is its main food source. It comes onto the land periodically, but the reason for this is not known. (Moon)

Names around the world

Trivia

• Highest HP among Water types in Gen 4: 111.
• Highest Sp. Atk among Ground types in Gen 4: 92.
• Taller than 43% of all Pokémon (0.9 m).
• Heavier than 52% of all Pokémon (29.9 kg).
• Base stat total 475, ranked #431 of 1,025.
• Its best stat is HP, ranked #52 of 1,025.
• One of 9 Pokémon that are both Water and Ground.
• One of 87 purple Pokémon.
• Number 37 of 107 Pokémon introduced in Generation 4 (Sinnoh).
• Part of an evolution family of 2 Pokémon.
• Can learn 62 different moves in Scarlet / Violet.
• Catch rate 75: about 9.8% per Poké Ball at full health.
• Appears in 11 distinct Pokédex entries.

Sources and fact-checking

• Stats, types, abilities, moves, evolutions, forms and Pokédex entries: PokéAPI open game data.
• Lore: written by pokee.si in our own words, researched from Bulbapedia: Gastrodon (Pokémon), Bulbapedia: Cynthia, Serebii: Gastrodon (Scarlet/Violet Pokédex).
• Pronunciation (GAS-truh-don): it follows how the English anime, games or official videos say it.

Last checked: 20 October 2026. Every sentence of the lore was checked against Bulbapedia, Serebii and the game data.

Explore

Water-type Pokémon · Ground-type Pokémon · Water/Ground weaknesses and matchups · Sinnoh region guide · Sticky Hold ability · Storm Drain ability · Sand Force ability · Compare Gastrodon · Full Pokédex · Type chart · All moves

Browse similar Pokémon

Gen 4 Water-type Pokémon · Gen 4 Ground-type Pokémon · Gen 4 Pokémon list · Purple Pokémon list · Water 1 egg group · Amorphous egg group · Pokémon that start with G · Snail and Slug Pokémon

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