All you need to bring to an event is a Photo ID (school IDs are allowed), a controller that does not violate the MLG Pro Circuit Rules regarding controllers, and a Parental Consent and Media Release Form
if you are under 18 years old (19 in Alabama and Nebraska). You also need to bring a printed copy of your confirmation email that you received when purchasing your pass. Other things you may want to bring would be money for souvenirs, a bag to hold your equipment, and a headset. It is also good to have a copy of the schedule for the event so you have an idea of when you will be playing and a copy of the Gametypes for your tournament so you know what to expect in the upcoming round.