We encourage all Trainers to abide by the Community Guidelines and Terms of Service whenever playing Pokémon GO, but especially while participating in Party Play.
However, if the host or a member of your Party behaves inappropriately, you can submit a report to Niantic for review by reaching out to the Pokémon GO support team. Note that, in order to take action on your report, you will need to provide the Trainer Nickname of the Trainer in question.
Once we receive your report, we will review the situation and take the appropriate action, including but not limited to issuing strikes against their account.