Let me link my demons again:
http://dffd.bay12games.com/file.php?id=10333
So, some of the demons are really squishy and buggy in adventurer mode so they constantly give off bursts of boiling extract, which is kinda hilarious, but doesn't do as much as you'd think for their combat potential:
I made a steel angel outsider, left her ungeared, and went and started punching demons in a demonic pit mini-tower, killed 7 I think before they finally managed to kill her.
Made a male angel (avatar of armok, avatars for short) outsider, dfhacked him some steel armor, elf leather cloak, and steel battle axe+shield, they come with natural skill 15 in the relevant skills. He killed quite a few of the squishier demons but a pair actually held their own for a while, a skink brute and blind brute, though a tarantula brute had gotten a lucky kick and removed an arm. It took a while to get through the thick clothing on the skink and blind brutes with "just" a masterwork steel axe.
Then I dropped his gear, dfhacked it into candy, put his arm back on with gm-editor, and dfhacked a plat war hammer to offhand, and headed for the main fortress tower where I find that while trolls hate goblins, they seem to get along with demons just fine... and apparently demons get along with humans fine as well:
There was actually a human master at the top of the tower too! Was... because, well, habits are hard to break.
After getting about 36 demon kills I went down and found some kids, figured I'd see how they did against demons...
Oh yeah, forgot about that.
I ended up hacking the arm off a steam demon and one of the elf kids sat there punching at it while I hacked more limbs off the demon trying to get the other kids to jump in, they ignored it, I got bored of it trying to push the elf and the elf kid missing it so I left them there.
Ranking: skink > blind=sloth > flame=tarantula=somethingfly > vomit/salt/brine
The flame demon outsider I made got quite a few dorfs killed, but kills didn't count since it was due to fire not combat.
Note that the flight gaits aren't listed right, I'll check on them later and see if I can fix them as I've got a race with different castes and two different gaits for the flight and running (angels and avatars) that works perfectly, but the flame demon was stuck at 1.0 movement.
I'm not sure if there should be an interaction for the boiling extract or if I was just supposed to be constantly spouting it, it was hilarious running around like that.
The skink/blind brutes wear the super super super freaky thick demon clothing which is ridiculously effective armor, I set the skink on fire several times with dragonfire and only managed to injure it slightly from the fire and burn the socks off I think? They're also very fast and agile so they'll be nasty as HELL in dorf mode, well done!