At last, here's Worm! I was waiting for this! I thought people would bring up Worm characters immediately, and I was kind of prepared for it, but this took longer than I expected.
1.) Suriel vs. Projected Siberian
The real answer to this is that Suriel analyzes the structure of the energy making up the Siberian projection and--depending on the mechanics of how the power works--either severs it from the source or deconstructs it, destroying the projection.
However, I suspect you wanted a punch-em-up, so let's take that case.
The Siberian's hit isn't enough to break Suriel's armor, but it knocks her backwards. At which point Suriel realizes this, does some calculations with her Presence, and retaliates with a blow that should knock the Siberian into orbit.
It fails, because the Siberian disperses any kinetic energy directed into her. All that energy has to go somewhere, so it's either absorbed by the construct itself or vented into her surroundings.
If it's absorbed by the construct, then Suriel has no choice but to sever, disassemble, or overload the construct, again depending on the mechanics of the power. If it's vented into her surroundings, then Suriel hits her hard enough to send a square-mile chunk of the city into orbit.
2.) Suriel vs. Zion
This is more even than anyone else vs. Zion, because Suriel can counter his most overpowered ability: Contessa's power. Her Presence is connected to Fate and has similar capabilities, so they can both see what steps are needed to defeat the other.
This would be a fight that would threaten Suriel, and I could see her contacting other Abidan for help. In the end, if she had to fight alone, it would be a close battle. This is an enemy she would normally call Gadrael, Razael, or Ozriel for.
I believe she COULD take it, but it would be difficult.
3.) Simon vs. Skitter
This would be the most irritating power Simon has ever gone up against.
As long as we are talking Skitter and not Khepri, I think Simon would get it. She still doesn't have superhuman speed, so while she's commanding her deadly cloud of insects, he just runs up in bullet time and puts a sword through her head.