I say basic control for now. I highly recommend DVD "Ride like a Pro" for your situation. It is EXTREMELY cheesy, but the guy teaches pretty well, and exactly what they need. I'm very glad I bumped into it a few years ago, I honestly think it made me a better rider overall.
They will be having just as much fun as in gymkhana, only at the speeds that a new rider will be comfortable with, WHILE getting important skills hones.
And they will progress much faster.