On the sim days that I've attended the aggressor is given different roles depending on the scenario. It could be that the instruction is not to fight if the victim gives the correct verbal and physical signals. It has also been the case that the aggressor is told to fight whatever signal is received. I found this valuable, as it gives the intended victim a chance to expose themselves to various kinds of violence and intimidation. This brings the pre-fight dialogue very much into play. On the two on one and two on two (or more) scenarios I've been in the aggressor may have the back up of his partner, or his partner may be the one trying to calm things down. It is a many and varied approach, trying to cover as much detail without watering down the intended drill. In terms of watering down the attack that certainly isn't the case. The quality and amount of protective equipment allows pretty much full power and while I've only ever been cut once, the equipment usually stops cuts and grazes. You feel the hits, but without the equipment you would have to ease off the power.