Gadjo
Doka
I did always figure that Wally was resistant to physical attacks, one more reason Homu couldn't win. I've always thought that the whole Mitakihara team+Kyoko could have defeated Walpurgisnacht, but Homura refused to try to unite them after the 3rd timeline. It works well with her general running theme of failure: she had all the tools she needed to win, but because she kept trying to do it alone, rather than working with Mami and Sayaka when she had the chance, she was doomed to failure.I still prefer the idea that magic confers a resistance to non-magical attacks, but that is an interesting theory.
It seems to me that Homura is actually capable of changing the future, it's just that she fails to beat Walpurgis. I prefer to blame it on her inability to work with others rather that just "fate".Homura can't beat Walpurgis because she couldn't the first time. She wished to protect Madoka. She didn't wish to save her, or change her future. Whenever you reach 12 on a clock, it always goes back to one. Homura cannot advance. She froze herself at the moment that defines her now as Homura Akemi, and that Homura cannot change her original failure.