It needs a decent primary attack skill.
If you envision the hovercraft to be light and fast, give it a medium ranged missile that deals low damage and stuns, but does extra damage versus certain types of units or even structures. This should make your hero interesting as it requires a bit of strategy and organizing to perform well.
On the other hand if the hovercraft is lumbering slow, give it a long range cannon skill. This would turn the hovercraft into a siege-like hero that deals powerful amounts of damage if left unchecked, but would require fast moving allies to cover its retreat should it come under fire.
The others skills should be supportive types, like the ones suggested by above players.