You can not become a robot in Sims 2, but you can however make one and make it playable!
There are two ways to do this. You can do it using cheats and using a workbench made available by the expansion pack 'Open for Business'. The cheat way will be first.
- Open up your cheat window by simultaneously holding down Ctrl Shift C. This will cause a blue box to appear at the top of the screen.
- Next, type " boolprop testingcheatsenabled true" (without the quotations).
- Go inside a playable lot (residential lot). Hit the Shift key and click on a Sim.
- Click "Spawn". Now click on "New Servo". If this option isn't available, click "More.." until it becomes available.
- Click on the Servo (The thing that now appeared), and choose Initialize. Now choose the gender! A window with text should appear, allowing you to name your Servo!
The non-cheat way is to buy a robot building station under Hobbies, Misc. Once your Sim gets their gold badge, they will be able to make a Servo.