The nine demons are not ranked in terms of strength, power, or anything else. Just the nine of them, as they turned out to be. The nine beta testers that were selected by the system to become them from the total number of those that were selected from the filtered choices. The choices were filtered to prevent a situation where there were nine of the same kind and/or type of demon. Also, the choices were unique and something that would be considered unexpected. If it were a well known creature, then how to counter them would be easier to do; however, this way was designed to be different, at least.
Even if the creature is known and/or known of, that would not change the fact that they are not normally used at this scale or level. So, dealing with them becomes a challenge in and of itself, as selection was from the three sources. The seven that were from the normal bracket of unique, fleshed out demon designs. The one that was picked from the interesting ideas that lack of detail made up for that. Then the one from the loser bracket, so to speak, as this one was from those that were rejected for being too common and used too often.
Nothing wrong with the " if it ain't broke do not fit it motto, however....
Variety is the spice of life.
Just because you can do something does not mean you always should, as making things more interesting could produce something that is different and unique, as the scenarios that pop up can be different as a result of not having so many commonplace and well crafted within the selection pool.
Thus, dealing with the selection from the loser's bracket that was created because if the other eight were being considered unique, different, uncommon, or just a neat concept idea, there being one that is overused and commonplace would actually stand out amongst them.
A selection from that bracket of those who did not make the cut to move on during any part of the selection process. Unique from those that did, as this choice ended up being:
Dragon.
One of the beta testers, when asked to create a demon, merely wrote down one word for it. That being the creature themselves, as they did flesh out, nor give it an interesting, unique concept. There was nothing that said exactly to do that. The process the system was using to select the other eight demons was never revealed to the beta testers at all. However, it was implied that there was to be some thought given to the idea, given that the character creation process was a herculean task in and of itself. They were creating everything and anything for their player character within the character creation part. They were allowed to make the exact character they wanted and have them be exactly how they wanted to be from head to toe. Everything they gave their character beyond their basic appearance was in the game world; however, none of the players were even given those things directly. They were expected to find them themselves, as they were things present in the world as they exist, but if they wanted to claim them, they had to find them and learn them. All on their own, with the exception of the nine demons that were given everything and anything the moment they were turned into demons.
The dragon demon was a player who fit a certain mold that rushed through the character selection process as fast as possible. Just leaving everything as default for the sake of bump rushing through the process itself. Despite being told that their character, once created, can not be altered without the same amount of effort and work it takes to do that normally. The option to change their form exists, but the process must be gone through or discovered. Thus, many players were just running around the game world as the default character appearance, with them having nothing, and even just skipping over the part about making a demon for themselves. They all just wrote down the first thing that came to mind and moved on.
That what was the mindset and appearance of the dragon demon. They were a generic default looking character with a typical choice for when wanting to skip all the stuff they viewed as unimportant to get to the game as fast as possible. Though having a generic looking face where they could blend in with a crowd of them would have been a benefit, as the other eight spent the time creating their character with more thought than they did, at least.
What they did next blew that advantage right away and then alienated, as well, enraging an entire group. The dragon demon did not have to worry about anyone ousting them from the other ten thousand players. That was never something they had to personally worry about, as why would they need to do that when they willingly did so themselves? They rampaged and leveled their own starting area, wiping out everyone who was there after flying over to it. They were able to take out and destroy everything that was in front of them, without anyone being able to do anything about it. Then, purposefully transformed into their player character form, declaring themselves the new overlord of this region. Incorrectly thinking that they were given the right to be the ruler of their own starting area, that was the role of the nine demons. The dragon demon was wrong, as they were given the right to do anything but everything instead. The difference is that they were given the right to dominate as a demon, but they were never given the right to rule. They could rule; however, that was not right, but a choice that has both positive and negatives to it, as the right to rule and the right to be ruled. Those are not the same thing as those with power, authority, and the will to do so. Their choice, however, did not remove the choices that other players and even demons still had for themselves.