2.5D typically means the game is rendered in 3D but presented with a side-on perspective that mimics a 2D sidescroller. C2 is a 2D engine out of the box, so it can't generally do what you're looking for here. There are a few ways around that with plugins to render 3D models, 3D models rendered out to sprites or just clever use of parallax to mimic a 3D space.
If you're really married to the idea of it being true 2.5D you might be better off with something like Unity, though. That would be better for console support too, because out of the big three C2 currently only exports to Wii U.