The Jennies would listen to their story, yes, but would most likely dismiss it as being a newcomer confused about arriving here so suddenly. Team Rocket has plenty of ways to hide their dorms via secret entrances, so it wouldn't be possible for this person to bring back the Jennies to the dorm. Even if they could find the secret entrance again, it would be closed and non-functioning.

And well, with no proof and a wild story (and the fact that all social ills are generally solved by ten-year-olds with their pets), the Jennies will be kind! Very kind! But they won't believe them.

Though they will probably hand them a 'so you've been transported to a strange new world' pamphlet and suggest the network to talk to other people who have experienced this.