I have seen some games where the objects have black borders around no matter what rotation or movement occurs to the object. I don't think it is the texture. More like GUI or something?
How would I do that effect? (the border i am trying to achieve is like the one when you select an object and it has that selected border)
One of the toon shaders allows for black borders, looks like the circles in this:
Is that what you're going for?
I would strongly suggest the "Flip normals, then upsize faces" trick.
Here are the steps below:
1: duplicate your mesh
2: scale the mesh just a LITTLE bit larger than your original mesh
3: FLIP THE NORMALS!
4: Make your new duplicated/upsized/normal-flipped mesh the color black(or chosen border color)
5: Now parent your duplicated/upsized/normal-flipped mesh to your original mesh(that you wanted to have a border on)
ta da! you now have a black border that will follow your character and render only as a border due to it's flipped normals.
there are many resources for many 3D-apps on this technique. here is an example of one that tells you how to do this in Blender.