Nothing is required except for a robot, a controller, safety goggles, and a joystick! Of course, it wouldn’t hurt to have parts, tools, chargers, batteries, and laptops.
Banners are not required. If you want you can make one, but my club has never used them. Pins and buttons would be pretty cool too but not required or necessary.
Tournaments will generally have at least 1 table for you to work on and store your robot. It’s usually about the size of a standard folding table or more. I don’t know if you would be allowed to bring extra tables or not–sometimes you’re not allowed to, depending on the tournament.
Other things you might want to bring: camcorder/phone to record matches, money/food for lunch and concessions, coolant spray, dremel/saw, notebook.
I’d ask your event organizer (on the first tab in robotevents.com) to ask what the pit configuration will be like and if there will be common tools or should you bring your own
Some events collect notebooks ahead of time so you may be left in the pits talking to a pit judge without your notebook to reference. So backup copies of pictures and things to explain to pit judges are sometimes good to have. Some students like to have a crutch like the notebook to stay on script/topic.
Banners are cool, but a word of caution, at every competition I’ve been at except for worlds the pits are tables set up throughout a room in rows, so chances are you will not have a wall by your pits to hang a banner.
One thing you should bring is some balls to practice with, as many events provide a practice field but no game elements.
And make sure you don’t forget batteries, chargers, some tools and spare parts. If you have some specially made parts on the bot like fancy-ly cut things I would also recommend making and bringing some spares of you can, just in case.
I have never seen an event with a practice field but no objects… Also remember to bring extra controller batteries, I usually carry most of the tools and batteries to every match but that’s a force of habit
A fanny pack is useful. You should probably carry a few of each type of allen wrench, fresh battery, orange USB cord, laptop, and a whole bunch of zipties to each match, especially if the pits are far away from the fields, just because Murphy’s law.
Fanny packs are the best! You might be the only person wearing one and get some funny looks but it is definitely worth it in the end. I carry everything @puzzler7 mentioned along with some candy(you never know when you’ll need a snack) and a laser pointer for alignment.