Depending on the complexity of your robot you can be a little judicious about what tools and raw materials you bring to the pit. Remember there's (very) limited space there.
Some teams do the "kitchen sink" approach and bring giant tool chests filled with tools and fasteners and spares. "Just in case" you decide to cobble together something completely new and unexpected, or complete a repair you weren't planning on. You will also be the best friend of any other team who needs that one obscure part or tool.
You could also pack only the things you're likely to need. If you've standardized on 1/4-20 and 10-32 fasteners, do you need to bring your team's entire 400-piece socket set, or could you get by with a far more portable 50-piece set?
Don't forget to bring a nice long Ethernet cable (15-25 feet) for use in your pit or in the practice field - wireless connections are not allowed. I would suggest bringing several in case you accidentally snap off the little locking pin on the RJ-45 connector.
Don't forget the most important thing: buttons to hand out
