Caustic Sewers, also known as CS, is a dungeon found in the Tanren Undercity. The green water in this dungeon can poison a water, flying, or levitating Pokémon, so bringing a Pokémon with Refresh will help you throughout this dungeon.

Dungeon Parts


Lower Floors

  • Floors 1-11

    Lower Floors 1-11

Middle Floors

  • Floors 11-20

    Middle Floors 11-20 and Upper Floors 21-30

Upper Floors

  • Floors 21-30


The Pokémon here are mostly Poison, Ghost, Dark, and Steel.

Lower Floors(1-10):

These floors are mostly pre-evolved pokémon and mid-evolved pokémon.

  • Koffing
  • Ariados
  • Nidorina
  • Nidorino
  • Golbat
  • Haunter
  • Skorupi
  • Seviper
  • Arbok
  • Bronzor
  • Stunky
  • Raticate
  • Gulpin

Middle Floors(11-20):

A few fully evolved pokémon like Gengar and Weezing. There's still a few pre-evolved and mid-evolved pokémon.

  • Gengar
  • Stunky
  • Weezing
  • Ariados
  • Arbok
  • Nidorina
  • Nidorino
  • Crobat
  • Forretress
  • Raticate
  • Koffing
  • Grimer
  • Muk
  • Seviper
  • Haunter
  • Duosion
  • Venomoth
  • Swalot
  • Garbodor
  • Dustox (Night)

Upper Floors(21-30):

The upper floors have many fully evolved pokémon and you can recruit a Trubbish on these floors at Dusk/Night. Also, you can find Trubbish eggs, but they're rare.

  • Nidorina
  • Nidoqueen
  • Nidoking
  • Bronzor
  • Drapion
  • Swalot
  • Stunky
  • Muk
  • Ariados
  • Garbodor
  • Ferrothorn
  • Trubbish (All times)
  • Weezing
  • Bronzong

Mystery Eggs:

  • Trubbish (Rare)


  • Relic Copper
  • Relic Silver
  • Relic Gold
  • Ekop
  • Rotten Apple
  • Kebia Berry
  • Oran Berry
  • Grimy Food
  • Grimy Berry
  • Stamina Band
  • Cleanse Orb
  • Recycle Orb
  • Trawl Orb
  • Mobile Orb
  • TM Toxic

Kecleon Shop Items

The Kecleon shop in Caustic Sewers spawns on 28F. Note that in case of a small room the shop may fail to spawn.

Name Price
Yellow Apple 250
Max Ether 250
Oran Berry 100
Sitrus Berry 150
Lum Berry 150
Antidote 250
Trawl Orb 350
Smoke Ball 250
Toxic Orb 500
Black Sludge 500
TM Sludge Bomb 5000
TM Venoshock 5000


The boss is a resemblance to Team Skull from Explorers of Time/Darkness/Sky, which are Skuntank, Koffing, and Zubat. Skuntank drops 35 Ekops when it's defeated. Koffing and Zubat drop 1 Tiny Mushroom each.

  • Skuntank
  • Koffing
  • Zubat

Dungeon Objective

As with most dungeons, the goal is to complete it and go to Ancient Caustic Sewers. Caustic Sewers is also a location where a Pink Silk may be obtained. This can be accomplished by unlocking the Sealed Chamber on 25F with a Silver Key and having the contents of the box contained appraised.


Secret Room:

  • TM Toxic
  • Poison Dust

Ending box:

  • TM Venoshock
  • Full Restore
  • Big Nugget
  • Max Revive
  • Purity Relic


Bring a Pokémon with Refresh.

Purity relic/Safeguard/Status immunity gems are recommended.

There is a kecleon shop at 28f


Caustic Sewers has one of the highest level ranges out of all the Tanren Undercity dungeons.