GRIMER's sludgy and rubbery body can be forced through any opening, however small it may be. This POKéMON enters sewer pipes to drink filthy wastewater.
Sapphire:
GRIMER emerged from the sludge that settled on a polluted seabed. This POKéMON loves anything filthy. It constantly leaks a horribly germ-infested fluid from all over its body.
Fire Red:
Sludge exposed to X rays from the moon transformed into GRIMER. It loves feeding on filthy things.
Leaf Green:
Appears in filthy areas. It thrives by sucking up polluted sludge that is pumped out of factories.