[IronicDeadBird]

Before we even get into defensive driving we should talk about things you can do when you don't have access to your robot. This years game is brutal if you know you are going in as a bruiser before you even hit the ground make sure the right people on the team know the right things about the robot. A good drive team can diagnose from the driver station what is going on with the robot and at the end of a match they need to be debriefed so when a robot gets to the pit possible kinks can be found and quickly eliminated. This is where a practice bot comes in really handy if you have one, otherwise its just about knowing your design.
If you don't have a practice bot you always have information you could brush up on (besides what lies in the rule book). With the amount of matches being recorded going up year after year there is no end to videos you can learn from about what good drivers do. A good understand of the game is crucial to understanding what you can do that is defensive while also still being valuable to a team.
When people say defensive bot most people jump to a wall bot but being a successful defender doesn't begin with just blocking shots. The safest way to stop a team from scoring isn't by letting them take a shot and by you blocking it, its by not letting them have access to those shots in the first place. You don't need a wall on a robot to stop shots if you instead stop an opposing team from even getting boulders in the first place then they can't take the shots anyway. If you do commit to a wall or a structure then make the most out of it.Never get too bogged down playing defense on one robot to lose sight of the entire match.
For scouting if you are doing a lot of focus on defense pit scouts need information on drive bases and stand scouts should be looking for patterns in driving you can exploit.

All this being said a perfect defensive robot is in the others teams way all the time but never in the way of their own team.