Elemental-weakness-exploiting Gambits are the best, especially coupled with the elemental staves that power up specific elements, but I don't remember when you get those gambits in original FF XII.

[Enemy: HP = 100% -> Steal] is always nice to have.
The White-Magic-Tank could probably use something like [Self: HP < 50% -> Cure]
If you have Reflect, you could also consider something like
[Ally: Any -> Reflect(ga)] + [Ally: Any -> Aero]
for big boss fights (Demon Wall I for example)