Yes, there is stunting, and frankly, all you need to stunt is an Advantge and there are several ways to get those. But there are a couple of powers that are meant to duplicate any other power that's reasonable for your fictional description.
Now, I'm not talking about Cosmic Power. Cosmic Power was a pretty wide-open power when ICONS was first released, but with the Assembled Edition, it's mostly just a slutty power description that will take any extra. "I have Cosmic Power...and I'll take Aquatic as an extra, and Animal Control." No, once upon a time, Cosmic Power was truly an opportunity for every power, but not now.
No, the two powers that really are meant for duplicating powers are Gadgets and Magic. (A slight change to Magic has made it encompass the "old" Cosmic Power.)
One of the things I liked about Mike Lafferty's Recluse write-up was the use of Gadgets to cover the web-shooters: Swinging was Gadgets 3, Binding was Gadgets 7 (I'm making up the ranks), and it allowed the web-shooters to do all the things they do in the comics.
Obviously, if you spend a Determination point, you don't need the attribute test. (It's not clear, but I suspect an Advantage works here as well as a Determination point. The rules only call out Determination points, though.)
The biggest disadvantage to both of them (I think--I don't have the rulebook handy) is that you don't pick a power that they emulate by default. (You do for Cosmic Power, for instance.)
Both require a page of preparation, but you can buy that off with an Extra: No Preparation.
Gadgets requires an Intellect roll against the rank of the device you have or are building. Swinging 2 is an Intellect test against 2. Binding 4 is an Intellect test against 4, and so on. Obviously, if you're naked on an island with nothing but fish skeletons and sand, the GM might deny you the use of your Gadgets ability.
Magic is a little more versatile and a touch more complex. When you get the power, you define the attribute that you roll against (Will is common, but it might be Awareness; Flex Mentallo might use Strength) and you get to define a specialty that will help, such as Occult, Power Ring Usage, or Muscle Mastery. However, Magic also has the Performance limit: you have to speak the spell, gesture with your ring, or pose magnificently. (You can buy that off with another extra, if you want.)
Magic offers Mastery, which Gadgets does not (officially): Mastery essentially means buying the power as an Extra, and then you don't have to worry about preparation or performance for that Mastery. Still, it's expensive from a point view, and it starts to look like Cosmic Power is a reasonable bet, then.
So if you're thinking that the problem with ICONS is not enough powers, try Gadgets or Magic.
- Gadgets: Intellect roll, page of preparation.
- Magic: A [choose one] attribute roll and a Specialty, page of preparation, and performance.