did you ever try this out? As far as I know you are correct, noone has completed superhero mode solo before. I have gotten to Darkseid solo, albeit using MM to cheat a bit along the way, but I cannot beat him. My best is with Superman, but I have a hard time once the greater parademons come in.There's too much going on and I don't do enough damage quickly enough to take them out before I die. I have all but given up on soloing him.
If you don't care about cheating, MM can phase shift through the entire protect superman level and complete it long before superman gets there. Otherwise it's tedious and annoying since there are no save points. It's hardest to make sure superman stays alive and I have never completed it without MM.
Yeah, as good of a feeling it is to complete this difficulty, it does kinda take the fun out of playing.
Another place that is ridiculously hard soloing is Green Lantern and the Flash breaking down the door before getting to the key. That was almost entirely based off of luck, whether or not I could whirlwind up the enemies fast enough to keep GL alive and then switch to GL to take out the doors, all very quickly so as not to run out of time. It took me over 20 times to complete it.
Anyway, I would like to see this completed and get tips on soloing Darkseid. If you do end up having trouble with Queen Bee, I came up with a strategy that works almost every time for me. It's posted here on Gamefaqs, just search the boards for it.
I didnt know there were three syllables in athlete: ath-a-lete! Thats amaz-a-zing! - Benchwarmers