You can bring in non-unique droids on Wat's reserves.
You can bring in unique Fringe droids on Lobot's reserves, but not unique droid characters that were in your original squad (any version). And don't overlook that Gha Nachkt's rapport only applies to non-uniques. Also, fit in a Battle Droid Officer if you have one, to boost all the non-unique droids' attacks by +4.
One thing droids have serious trouble with is stealth. If you have Zuckuss Bounty Hunter, you might work him in so you have an accurate shooter (with Whorm's twin!) and access to Force Sense for a couple rounds. A Battle Droid Sniper (or two) might be helpful as well (more accurate). In that case, an ASP-7 or T1 Bulk Loader droid would be useful to lift it into position to attack so it doesn't get picked off before you can get some damage out of it. The T1 itself is a tank with 140HP and is good for getting in the way of approaching Jedi, who won't want to get hit by it for 40/50 damage per swing.
Just a few thoughts there .... at 500 points a lot of things are possible (both for and against your squad).
The squad looks very powerful, but you'll want to think about how to deal with Stealth, Evade etc if you see those types of builds regularly at your LGS.
You may well be aware of the things I mentioned, but either way - I hope that helps
