It has recently been found that Grimers are formed in waste-processing plants, and can move into towns via the sewers.
This card was released in the Japanese Rocket Gang expansion, with Poison Gas's effect causing the opposing Pokémon to be Poisoned. When it was printed in the English Team Rocket expansion, the effect was changed to cause the Defending Pokémon to be Asleep. The artwork was also altered for this print: Grimer's pupils were repositioned, as in the Japanese version it appeared to be looking up the Lass's skirt. The artist, however, denied this was the case.