Start a game on level five - this will give you enough enemies and power-ups to get this done in one or two tries.
To get an AI droid on your side, collect power-ups as they appear. You'll earn them by blowing up enemies. The droid normally shows up as the fourth power-up - generally after you unlock the Jump. When you have your droid, try to get captured by one of the standard enemies - the ones that drag you down the screen. Let them get you and drag you away. The droid now needs to shoot them in order to release you. If you manage to get far enough down the screen before he gets his act together, then the trophy will pop.
This is a bit of pot luck but you can help your chances by making some distance between yourself and the droid before you get caught. If he is on the left side of the screen, rush over to the right and get caught by an enemy. By the time the droid makes his way over and rescues you, you should have made enough distance. Failing that, you'll lose a life and have to give it another go.