Thickly covered with a filthy, vile sludge. It is so toxic, even its footprints contain poison.
Blue
Yellow
Smells so awful, it can cause fainting. Through degeneration, it lost its sense of smell.
Gold
They love to gather in smelly areas where sludge accumulates, making the stench around them worse.
Silver
Its body is made of a powerful poison. Touching it accidentally will cause a fever that requires bed rest.
Crystal
As it moves, a very strong poison leaks from it, making the ground there barren for three years.
Ruby
From MUK's body seeps a foul fluid that gives off a nose-bendingly horrid stench. Just one drop of this POKéMON's body fluid can turn a pool stagnant and rancid.
Sapphire
This POKéMON's favorite food is anything that is repugnantly filthy. In dirty towns where people think nothing of throwing away litter on the streets, MUK are certain to gather.
Emerald
It prefers warm and humid habitats. In the summertime, the toxic substances in its body intensify, making MUK reek like putrid kitchen garbage.
FireRed
It is usually undetectable because it blends in with the ground. Touching it can cause terrible poisoning.
LeafGreen
Thickly covered with a filthy, vile sludge. It is so toxic, even its footprints contain poison.
Diamond
A toxic fluid seeps from its body. The fluid instantly kills plants and trees on contact.
Pearl
Stadium 1
Becomes indistinguishable if it hides in dirt. Touching its sludge-covered body causes horrible poisonings.
Stadium 2
They love to gather in smelly areas where sludge accumulates, making the stench around them worse.
TCG
Dark Muk: Muks appear suddenly, spreading sludge everywhere. Whenever one appears in a city, panic ensues.