Look at Carver on Einstein:
4499 was the primary defensive bot, but the key to that alliance winning was a combined effort. Every robot contributed constantly, that is the reason they beat world class alliances.
4499 stops the blue alliance bot for 40 seconds. Start at 1:20 to see them set up their defense. 4911 also pesters the robot trying to fill the switch.
4499 absolutely shuts down 1323’s scoring capability. 1323 scores a few cubes, but their speed was way slower leaving most of the scale work to 3476. 1323 had no uncontested scores during the match. Also watch midway through that 4911 is about to grab a cube, but they see an opportunity to trap 1323, they immediately back up and pin them making them drive the long way around. This also speaks to playing from a slight lead so you can afford to play defense the whole match.
The whole alliance pesters 1319 the whole match. Also note that as Red feels they may lose their switch, all three robots come back to maintain control.
I think the best defense is being situational. Being able to slow down the other alliance just a little bit makes a big difference in the long run.