During the season we were on both sides of having defense on our alliance (that is being a captain and picking a defender and being picked to be a defender). We asked questions like:
What type of drive train do you have?
What type of wheels do you have?
How many and what type of drive motors do you have?
How much does your robot weigh?
How many years has your drive team been on the drive team?
And before every match that we had a defender we would make sure that they knew all relevant rules on defending (Pinning, ramming, etc.)
We asked these questions during pit scouting and took it into account during our selection process the night before the day of alliance selections. We didn't actually ask about cheesecaking a blocker and it did not prove to be necessary because we won the event.(MAR Mt. Olive 2016)
At MAR District Championship we were chosen to be a defender. They asked us if we'd be willing to put a wall on our robot and the answer was "definitely". We were a very light robot, pushing wasn't really its specialty. But that's okay! Good defense last year proved to be less about pushing robots and more about strategic playing. We would park our wall in front of a robot and just wait for them to shoot. Yadda yadda I'm getting away from myself here.
The moral of the story is that while all of that previously mentioned robot things are important, you need to make sure that whatever team you pick as a defender knows how to hit the important elements of defending for whatever game you're having them defend for. (Defense strategy discussion can be somewhere else. I've digressed enough

)