I think Metal Knight may be the most "Dangerous" hero, not most powerful, most dangerous.
I watched Justice League Doom (Spoilers-->):
I think Metal Knight may be operating in the same way, Drive Knight may know this and that is why he warned Genos not to trust Metal Knight. I believe MK may have gathered enough info on each of the heroes, particularly the S-Class, and has methods and robots designed specifically for taking out each of them out. All the heroes except Blast because he is a ghost right now.
In the Web Comic (more spoilers-->)
If he was able to build the Hero Association HQ so durable that it could survive a bombardment powerful enough to level a whole city, then i could imagine he must also have robots made out the same material and are just as durable to tank attacks from guys like Metal Bat and Tank-top Master. Remember the massive construction robot that appeared to repair City A, the entire Tank-top army stood no chance, now imagine if that robot had some high tech weapon capabilities on it, not many people or even monsters could compare. Not to mention NO ONE, not even the hero association knows where he is so if they destroyed his robots he could just use Intel from that fight to build even better robots and they would have noway of stopping him because they can't get to him.
I don't know what Metal Knight is planning but if he ever went rogue, which he just might, he would surely be one of the greatest threats the heroes ever faced.
I watched Justice League Doom (Spoilers-->):
in the movie Batman's secret contingency plans for how to kill each of the Justice League members fell into the hands of some villains who used it against the JL and after that the JL couldn't trust Batman anymore so he left the league.
I think Metal Knight may be operating in the same way, Drive Knight may know this and that is why he warned Genos not to trust Metal Knight. I believe MK may have gathered enough info on each of the heroes, particularly the S-Class, and has methods and robots designed specifically for taking out each of them out. All the heroes except Blast because he is a ghost right now.
In the Web Comic (more spoilers-->)
after Saitama destroyed MK's security robots, MK became interested in how Saitama was so strong.
If he was able to build the Hero Association HQ so durable that it could survive a bombardment powerful enough to level a whole city, then i could imagine he must also have robots made out the same material and are just as durable to tank attacks from guys like Metal Bat and Tank-top Master. Remember the massive construction robot that appeared to repair City A, the entire Tank-top army stood no chance, now imagine if that robot had some high tech weapon capabilities on it, not many people or even monsters could compare. Not to mention NO ONE, not even the hero association knows where he is so if they destroyed his robots he could just use Intel from that fight to build even better robots and they would have noway of stopping him because they can't get to him.
I don't know what Metal Knight is planning but if he ever went rogue, which he just might, he would surely be one of the greatest threats the heroes ever faced.