You can use shapes and masks in any Final Cut template type.
In general, use of shapes should be limited to generator templates. Shapes are ideal generator template elements because they can be scaled in Final Cut Pro X without degradation. (However, too many shapes in a template can adversely impact performance in Final Cut Pro.)
When you add a shape to a placeholder layer, the shape is converted to a mask. When a template with a masked placeholder is applied to a clip in Final Cut Pro, the mask is applied to the clip. Objects in the template outside the placeholder are not affected.
You can publish mask parameters (Roundness, Feather, and Mask Blend Mode, and so on) so they are editable in Final Cut Pro. However, the onscreen mask controls in Motion are not available in Final Cut Pro. To reposition a template mask in Final Cut Pro, publish the mask’s transform parameters (located in the mask’s Properties Inspector). For more information on publishing, see Publishing Parameters in Templates.
For more information on working with shapes and masks, see Using Shapes, Masks, and Paint Strokes.