The way I handle Retainers, primarily Ghouls but also things like Spirit Slaves or whatever, is as is implied in the V20 and Revised books. Ghouls are very good at one thing, or pretty good at a few things, and they have one significant flaw. I don’t have full character sheets for them.
“Very good” is about 8 dice. “Pretty good” is about 6 dice. A flaw is something like being kind of stupid, or not so loyal, or over-reacting, or absent-minded, that kind of thing.
When creating a Retainer, go ahead and define what they’re very/good at, and what their flaw is. Or I can come up with those as implied by the concept you give.