Grimer

“Appears in filthy areas. Thrives by sucking up polluted sludge that is pumped out of factories.”

— Pokémon Red

“Made of hardened sludge. It smells too putrid to touch. Even weeds won't grow in its path.”

— Pokémon Yellow

“As it moves, it loses bits of its body from which new GRIMER emerge. This worsens the stench around it.”

— Pokémon Gold