my silly sp question is this. If a character like hulkbuster for example has his running shot/charge sp outwitted, does the outwitter have to specify which power he is outwitting or just the special power by name (flight stabilizers) to cancel both?

He can only outwit "Flight Stabilizers". He can't outwit just part of it (just the charge or running shot).

Right.
Your opponent outwits a power by name. In this case, that power would be flight stabilizers and it would counter every element of that power, just like countering combat reflexes prevents a figure from using the defensive bonus, the elimination of knockback damage, and the voluntary knockback.
Though my experience is that they will not say "flight stabilizers", they will say "Hulkbuster's movement power". Close enough, though.