Scoff. SCOFF! "i do not!! everything is completely essential to how i preform!" Knowing Mettaton, preform is the key word, here. He's not talking about functioning; he's talking about showing off. "there's not one thing i can go without!"

A keen eye can, despite the singe, make out labels inside of the robot's shell. Cables are connected to things like "burners", "morning dj soundboard", "glitter hands", "pen finger", "japanese language mod", "family-friendly censor", "chainsaw", and "snail release".

It's possible Mettaton is exaggerating about needing all of those.