If you don't file as an LLC, then you can file as a QJV, where each spouse includes a schedule C in their own name that reports their share of income and expenses (it could be, but does not have to be 50/50). Both schedule Cs get attached to your 1040 with the rest of your income and deductions.
Another option that avoids a partnership return (form 1065) would be for one spouse to have the business (schedule C) and pay the other spouse a wage on a W-2. This has different paperwork challenges from a 1065, but may still be more complicated than filing as a QJV.
If you decide to form an LLC, then you have to file a partnership return unless you are in a community property state. Legal protections offered by the LLC form vary from state to state, you should always talk to a local attorney before you form an LLC.
