Special Form on my wordpress site

I need a special form that a user can fill out for my website. I need a form that is able to track user to user challenges including acceptance and rejections. For example user A wants to challenge user B to a mile foot race. Best time wins. User A fills out the following information: Your username (autofill) Opponent: (access user database as you type) Type of race: 1/4 mile best tim, 1/2 mile best time, 1 mile best time. Message: Submit Also by entering this information it sends an email to the user and admin so the admin can manually track the challenge. I am using wordpress with the tesseract theme and buddypress for user database. Happy bidding