I can definitely answer this one: My stoker/wife had basically never ridden a bike or at least largely forgotten how to (she suffered a stroke about 10 years before we met and hadn't ridden since). To be honest, she has always been a great stoker and might even have been easier to learn to tandem with than an experienced cyclist. When we first bought our tandem (having never ridden one), I first tried it out with a friend who was an experienced single bike cyclist. I was all over the road and found steering extremely difficult, and my wife was quite nervous after watching us how it would be for her. Once she got on the bike, however, I found it far easier to maneuver with her than with our friend. Lacking any experience with bikes, my wife made no attempt to steer as we went through turns (as our friend had tried to do, forcing me to counter steer and fight their input), and learned to respond to my style of riding directly through the timing chain. Her cadence quickly matched mine, and she almost entirely adopted my riding style because she didn't know anything else.
When I've read some threads on here about how people communicate with their stokers, and commands they use, I was actually quite surprised. While we do talk a good bit while riding, it is rarely one of us giving commands about the ride itself. Instead, the vast majority of our communication on the bike is non-verbal. My stoker knows to soft-pedal instantly if I start to do so, making shifting seamless. If I start to coast for any reason, she instantly does as well. When stopping (one foot down for me, she stays on the saddle and clipped in) she just waits without moving around till I start to pedal and immediately pushes as hard as possible unless I slow to clip in my second foot. I don't tell her whether I'll clip in on the first pedal stroke or later (depending on traffic), she just seems to know. I think she is truly the perfect stoker because all of her habits were developed around being my stoker.