I find it fascinating to note how peoples' Enneagram type is contained or at conflict with their astrological birth chart. You can have synergy between the two, or you can have a real battle to get the shadow stuff integrated into a workable dynamic where you can get some flow in your life.
Someone could be having a veritable war within themselves if they've got two very different, conflicting energies that don't get along, and it can result in a stop-and-go quality to your life's flow where nothing really gets off the ground. On the other hand, they can have complementary energies and life unfolds without much inner searching. For example, Donald Trump is a fun-loving Gemini with an ascendant in pushy Leo and a Sexual Enneagram Type 8- there are quite a few overlapping traits those three archetypes share. Not much reason to sit and ponder his approach to life because there's little inner conflict prompting him to do so.
There are many tools you can use in coaching. Obviously I think everyone in the mental health profession should know the Enneagram, but astrology can step in and help sometimes. You can describe to someone the essence qualities of their Enneagram type, and their levels of health, and they can develop an awareness of their red flag moments, they can develop an awareness of their bodies and be able to "catch themselves in the act", (they can even learn about the Greek/Egyptian shape and volume associations and claim them as their birthright), but just like the unfolding process is sped up and enriched by adding the Enneagram to a meditation practice because it gives you a visual -the map of the psychic structure that you're unfolding- so also astrology can also speed up and enrich the process by helping you understand the energy with which you're unfolding. Libras unfold on their tiptoes, dancing to some kind of romantic operatic ballet, Leos unfold in a pimped out Jeep driven by frat boys with a bunch of girls in bikinis in the back seat, Scorpios unfold in a safe with multiple combination locks, and Virgos unfold in an Amish dress with a full-length slit up the side. And you can be male or female, and any Enneagram type with any instinctual stack and still have this other energy to reckon with.
I have four planets in brash and loud Leo, but you wouldn't have been able to tell I had any Leo at all until maybe a few years ago because that big energy was so curtailed by the introverted, inward-directed movement of the Self-Preservation Enneagram Type 4. I knew I was intense, but I didn't know how to give expression to it. Type 4, especially the Self-Preservation subtype is underexpressive, melancholic and self-doubting; Leo is arrogant, the life of the party and the center of attention. You have to figure out how to have these two huge archetypal energies work together in sync within you. It's learning to dance with your shadow instead of this jerky movement back and forth between repressing/disowning your shadow, and wanting so badly to express it and having it coming out in awkward ways.
Your astrological sign is another level of archetypes you have within you. You're complicated. If anyone knows another good way to describe the interplay between the two systems, I'm curious and I'd like to hear about it.