Based on some extra analysis AKA Doborog's comment, I decided to redo the counter structure, instead writing the counters and characteristics for each robot enemy (NOTE: Most robot names are non-official, unless Doborog decides to adopt them):
MK1 Sword Fighter: Mostly a nuisance when in small numbers, but in larger numbers it can distract you from stronger enemies and even overrun you. It is easy to kill, but in large numbers I'd reccomend a hammer, due to it being unblockable, or fire breath, basically any unblockable AOE attack to take down multiple enemies at a time. DANGER LEVEL=1
MK1 Combat Archer: Again, mostly a nuisance, but can easily kill you if you're not paying attention. You should always try to fight archers with at least Block Arrows I swords, and NEVER turn your back to them (Kind of like weeping angels or something like that... *shiver*), Block Arrows III makes them a joke, and Fire Sword makes it so reflected arrows catch on fire, increasing the PTK of the shots. DANGER LEVEL=1.5
MK1 Hammer Enforcer: The only other MK1 robot that is actually a threat, its hammer has a longer reach than a sword, and it has some punch packed to it. Fighting from a distance is reccomended, so, trust your bow and the Hammer bot's possible stupidity. If you don't have a bow, try using a sword, and not a hammer, unless your hammer has Hammer Size II or III, due to the sword's increased speed, fire is also a good counter against it due to its larger body size, which makes the MK1 Hammer more resistant to attacks. DANGER LEVEL=2
MK1 Jetpack Interceptor: The most powerful MK1 robot, its jetpack can be used to dash around the arena, and its ability to hold its sword in place while dashing makes it a formidable foe, its also extremely tough to hit it with a bow without knocking it down first. It is, though, possible to kick the Jetpack while its dashing, if you knock it down it will take a good while to get up, thus, get the kick and happy MK1 Jetpack hunting! DANGER LEVEL=2.4
"Spidertron 5000" MK5 Arachnid Bomber : It might seem imposing and terrifying at first, but its actually just annoying, the bombs it lobs do basically no damage, and the greatest danger you'll get from this oversized deformed spider will be getting knocked onto traps, it can be easily killed by an arrow to its weak point, or a timed sword swipe mid jump, fire is reccomended, because, if you manage to miss the weak spot, the spreading fire will still have a great chance of destroying it. DANGER LEVEL=1.9
MK2 Sword Fighter: Imagine a MK1 Sword, but slightly stronger and smarter, yeah, it's still simple to kill this guy. DANGER LEVEL=2
MK2 Combat Archer: Read above, but replace sword with archer. DANGER LEVEL=2.5
MK2 Hammer Enforcer: Yup... you guessed it, read above but replace archer with hammer. DANGER LEVEL=3
MK2 Jetpack Interceptor: Alright, this is the ONLY MK2 robot that isn't just its MK1 variation but slightly stronger and smarter, this is true NIGHTMARE incarnate. It is extremely quick, making even KICKING, which is, by the way, its weakness, tough, if you find one of those in the arena, pray that another robot kills it before it gets close to you. It's basically like this: "In Danger Zone Arena, you don't kill Jetpack 2, JETPACK 2 KILLS YOU!" DANGER LEVEL= "IT'S OVER 9000!!"
MK3 Sword Fighter: This is the (other) nightmare of bow only challenge, this robot has Block Arrows III, and its quick, smart, and resistant, use, and abuse fire on this one, as the smallest swipe might still burn this guy's arm off. DANGER LEVEL=3.2
MK3 Combine Archer: This used to be the most powerful robot in the entire game, dethroned by the MK2 Jetpack, and then lowered even more by the MK4 Combine Archer. This masterpiece of a human sized war machine is the closest you'll get to multiplayer at the moment, it fires Arrow Width III arrows normally, but, when you get close, it pulls out a sword and starts swiping at the player! If you manage to get away, it will start arrowing your face again, I reccomend using the previous Sword/Archer weaknesses on the right times, as to not get killed by this guy. DANGER LEVEL=5
MK3 Hammer Enforcer: Imagine a MK2 Hammer, on steroids, and with a BIGGER hammer, yup, this guy is going to hammer your human mind out of your robot body in an instant, great evasion skills required, fire and jetpack are almost a must, or, you could try and marksman it out of the arena, as its rather big... DANGER LEVEL=4.8
"Spidertron 6000" MK6 Arachnid Bomber: Remember how Spidertron 5000 was easy? Well, this guy's tougher. But still quite a pushover if you know what you're doing, two accurate shots are enough, but, if you don't have a bow, you'll have to chop its legs, as its way too tall to hit with a jump swipe, fire helps, and jetpack can be used by circling around it and putting your sword to the side. It's still kind of a pushover. DANGER LEVEL=3
MK4 Sword Fighter: Imagine a MK3 Sword with fire. It's just hell, nuff said. DANGER LEVEL=4.9
MK4 Combat Archer: Read above, but replace MK3 Sword with MK2 Archer. DANGER LEVEL=4.8
MK4 Combine Archer: Alright, this one is THE toughest enemy (MY OPINION) at the moment, it's a MK3 Combine Archer with fire, what could go wrong? DANGER LEVEL=666666.666
MKX Jethammer Enforceptor: Ugh... imagine the power and size of a Hammer, and the speed and agility of a Jetpack, ta-daaa! You have this abomination of a robot that is only beaten by the best players. Also, some free fire for you, YAY! DANGER LEVEL=10