Officer Jenny comes from a family with little variation among the genes, as all the jennies from every city in Pokémon all tend to look alike. At one point there is even a picture shown of all of officer jenny’s sister’s and cousins, and it’s very difficult, if possible at all to tell them apart. Officer jenny is very loyal to her job, and that’s why her most used pokemon is growlithe, the loyal (fire ^_^) puppy Pokemon. The other Pokemon seen with Officer jenny are spinarak, and a gastly.
Ash, misty, and brock/tracy tend to help the jennies out from time to time when team rocket is involved, which is quite frequently; especially in the episode “ pikachu revolts” where butch and cassidy, the other two renowned team rocket members made everyone’s Pokemon turn against them with a drowzee’s hypnotic waves. For some odd reason, Brock seems to take a liking to the jennies. Dunno whats wrong with him though, they all look alike.