Is it possible to achieve cell shading with Unity iphone, and how would this be achieved? and could it be done on Iphone basic?
through double mesh and having the dublicate be slightly larger, inverted and black colored yes.
but other than that, not really
I did what Dreamora suggests in Alpha Wars Orion.
Download and see results, it’s free 
http://www.moctezumagames.com/orion.html
That’s not cel shading, that’s outlining a character. Big difference. Cel Shading effects the shadow, has nothing to do with the cartoon outline. Though they are commonly used together.
Yeah, you’re right. Outlining isn’t equal to cell shading. Cell shading is something like a gradient but with more levels (I’ve used some plugins for Maya and the toon shading from Maya and all are based on gradient). What you could do is to make your texture look more like cartoonish style. Use in Photoshop from filters “Poster edges” and then a “Cutout” filter. Play even with removing noise or smudge effect. And for the terrain texture if you have one, reduce the noise of it first and then apply “Paint dubs” from filters. When you make poster edges you will have also inline not only outline, so this is visually better. Hope that helps
DariuF, I believe you’re forgetting to take into account the third dimension. 
Nope, I’m not forgetting. That’s for sure. If you have your UV’s made properly, and not generated automatically you can make every kind of texture you want. For example, have you played Street Fighter 4 on pc?And belive me, those characters are not prerendered. They are fully 3d with toon shading made from texture.
Or play the last episode from Prince of Persia.
Each of those games you mentioned uses a unique rendering style, that is certainly true. But a texture is static. It doesn’t react to different viewing angles or light. What you’re talking about is not toon shading.
made from texture but through a pixel shader that maps the 256 light attenuations to the toon texture levels