What damage abilities, if any can soaring figures use against ground based creatures?

none, unless you have Hyper-Sonic Speed.

You can't even outwit.

Soaring characters can only interact with other soaring figures in combat. If the character begins the turn in soaring mode, they may use a move point to come down and execute a Charge, Running shot, or HSS flyby, and in the third instance, may return to soaring after the attack, but that is about it.
Their isn't really a whole lot they can do from up there anyway. I think they can make a Barrier, I'm not sure about Perplex or Outwit. Maybe someone else can list all the options.

You can indeed use Barrier (and Smoke Cloud) at your full range when Soaring.

Although Psylockeslover covered the list (barrier and smoke cloud) I'd just like to reiterate for anyone reading this, a soaring figure can not outwit or perplex a non-soaring figure.

Thanks all, it really helped a lot