FCP does not do 3D operations. Motion allows you to animate effects in 3D space but it is not a 3d object manipulation program so you can't import 3D file formats like .obj, .3ds etc. There are some plug-ins that imitate 3D objects inside Motion and FCP but you just can't import "real" 3D objects.

Typically, for film and  TV 3D production methods, 3D animations are rendered and then composed in video post. This is where Motion's 3D tracking can help with special effects. 

For NFL Football bumper types of motion graphics, you need to use something like Cinema 4D Studio which has some pretty cool 3d object motion tools for animated arrays and other things.

Mark