Here is the full list of all 35 Droid Assault achievements.
8 droids in ascending security order
Fried 100 robots
Destroyed 100 robots with the disruptor
Everything-proof and maxed-buffs droid
Started a level with 8 droids, finished with only 1
Captured 3 9-series robots in same squad
Crushed 25 robots in doors
Defeated a boss with only a Sec Level 1 droid remaining
Maxed every buff on a droid
Completed Arcade Missions
Captured the Ultimate Droid
Flame, laser, and disruptor resistant droid
Achieved security level 9
Got Red Alert twice on one level
Maximum Recharge buff
Achieved security level 8
Escaped with 0 hitpoints and no squad
Maximum Overdrive buff
Defeated Level 40 Boss
Maximum Damage buff
Achieved security level 7
Maximum Armour buff
Command a full squad of 8 droids
Achieved security level 6
Maximum Battery buff
Defeated Level 30 Boss
Got Red Alert status
Achieved security level 5
Achieved security level 4
Defeated Level 20 Boss
Defeated Level 10 Boss
Buffed a droid in every aspect
Achieved security level 3
Achieved security level 2
Achieved security level 1