I want to file suit in small claims court, but can the guilty party be garnished for payment?

I am suing my SOON TO BE ex in small claims court for unpaid bills (car judgements & IRS payments). Will his pay be garnished for this claim?

He won't be "found guilty". "Guilty" is a criminal term.

If he is found liable, and a judgment is entered against him, yes, in most states you will be able to garnish the non-exempt portion of his pay.