In the case that they were hostile, then we simply go the nuclear option and they get wrecked to all hell.

Pet wolver.

There'd be Knights downtown begging for Energy.

The knights would fight hard and well... for an hour or two. Then they would run out of mist and the humans would have 22 uninterrupted hours to kick the living crap outta them. Unless a scheduled reality reboot cuts their fight time down even further. Then they're really screwed.

+10000000000000000000000000

Cobalt is standard issue. Just remember that it is highly resistant to piercing. Then remember the average Spiral Knight's arsenal has infinite ammo, and they have force field projectors, again resistant to piercing because they're using defender series. They also have reusable explosives (!!!), so they could probably level structures pretty fast. In any sort of urban combat scenario, we would get WRECKED. Our only real advantage is that we have vehicles. Some of their more specialized units could still neutralize our vehicles with shivermist, polaris, etc. Their most elite squads with Guardian shields, Striker boosts, and Recon Cloaks would be EXTREMELY vicious. Our best hope is aerial domination over them. Continuous airstrikes would eventually deplete their soldiers spare energy. Then again, the Spirals have shown they've adapt at reverse engineering technology, so if we don't stop them from gaining a foothold, they might gain our technology and mix it with their own, making jets with shields, stealth systems, etc. Also, nuking them wouldn't really work - we would devastate an area with radiation, preventing ourselves from occupying the region, whereas they could use energy to revitalize themselves, and then simply use a remedy pill to remove the effects of radiation poisoning.

I say we work with them to see if they can help our energy problems, and, see if finding a way to harvest the core without any damage to the earth, thus they could power the skylark and help us! simplez!

Revived by other knights and healing on heart pads somewhere within Haven. You're probably unconscious if you return automatically, so you heal during the loading screens.

But that won't be a problem once we've carpet bombed Haven. ...after stealing all of their Snipes. Can't hurt the Snipes, they'll destroy us all.

As far as individual knights go... they might have their shields, but all fall down before the mighty clipboards and floppy discs. We have tons of those, and they deal a reasonable amount of shadow damage, so we can get rid of them with our all-powerful office supplies.

I would punch their nuggets and throw them in a ditch

Yes, you are completely correct in that the Knights have distinct advantages over humans, but you forgot one thing:

Although it is not canon, it is probable that the Knight are partially or fully integrated into their mechanical suits. This would mean that they are at least partially susceptible to a virus. All we have to do is infect one Knight, and any simple virus (I am talking computer virus) would spread, with the knight having no means to stop (they do not appear to have that much knowledge about how their own armor utilizes its abilities).

This of course would be a last resort, as this is essentially chemical warfare.

They have poision defence. Again we have Aerial advantage since they cant shoot up in the air. We be fine in towers with sandbags since they cant jump too.