You need to have a dominant gene in order not to hit normals.
Co-doms (or incomplete dom) will throw normals because they're not dominant traits. But more genes you have in play, the chances of normals decrease (theoretically).
Example:
Lesser Black Pastel Pinstripe can render normals.
Bumble bees can have normals because it can donate a pastel gene or a normal gene. A spider gene or a normal gene. And a Spider Pastel gene.
But a Super Pastel Spider will render at least all pastels. Super Pastel is the homozygous form of a pastel. Pastels can be seen as a visual het of Super Pastel.