Wendy only appears in a single episode: "Dues and Don'ts". She works in the Human Resources department of Team Rocket. When Jessie and James have their membership in Team Rocket suspended, Wendy tries to convince Giovanni not to let them rejoin. It turns out she has a grudge against Jessie for sticking her with the bill for a fruit smoothie a long time ago.
In the end, Wendy gets her revenge by adding the price of one fruit smoothie to the list of expenses incurred by Jessie and James.