Gambits are a list of conditional commands in priority order. They are formed of two parts, gambit, which is the targeting condition (such as "Ally: <50% HP" would target ally that'd falls below 50%), and action which is executed to thus selected target. They are read from the top of the list, first one that matches is executed then started reading from the top of the list again.
In FF12 the action can be any ability or item the character in question can use. In here I guess we would have list of skills based on the class of the squad member. I would also like to see commands "move to player" and "move to target".
I'm aware squads are rather minor part of the game, but some other minor parts of the game get improved as well time to time.