The Trade Federation's Mechs are some of the best in the game, as they can be upgraded with both Advanced Redesign and Technicians; aside from the Trade Federation, this is possible only for the Galactic Empire.
Although they have some of the worst flying units, lacking many Airbase technologies, they do boast excellent Anti-Air Fortresses, which are given +3 Anti-Air Attack Range.
As for the offensive-defensive capabilities of this civilisation, it might be said the Trade Federation is rather defensive oriented. Their unique technologies granting cheaper buildings, cheaper technologies, and faster ore collection for towers seem to be favouring a slow, defensive and late-game approach.
Their unique unit is the Destroyer Droid, also known as Droideka. In its elite upgrade, it is given an individual shield. Given the speed of and all-roundness of this unit, once upgraded it is perhaps most efficient to use it for quick hit-and-run tactics, retreating once the shields are depleted, only to strike back once the recharge is completed. It must be kept in mind the individual shields are useless when the unit is kept defensively at the player's base, as the fixed Shield Generators would be granting them double HP already.