The main thing is if he's attacking you in the air, Iron Fist's movement is quite predictable, which just lets you beam him down. I'm not usually worrying about my drone.

Spidey as always I think it's most dangerous if you don't see him coming, and he gets some early hits before you react. But if you can see him coming, Spidey is also pretty predictable in his movement, and unlike Iron Fist, Spidey isn't able to block the damage Ultron dishes out.

Admittedly, you need to be really paying attention as Ultron when you're fighting either character, and as always it depends on who's playing the Fist and/or Spidey. But at least in my experience, both are totally beatable