A Subaru with a regular manual transmission can be FLAT towed (all 4 wheels on the ground) in neutral with no damage. To tow an automatic or CVT Subaru it must be trailered with all 4 wheels OFF the ground. NEVER dolly tow any Subaru unless the drive shaft has been removed and then ONLY with the rear wheels on the ground.
The manual transmissions have a mechnical differential controlled by a viscous coupling which is a passive system. Lubrication is a splash type which is passive as well. This allows flat towing as long as the gearbox is in neutral.
Some automatics and all CVTs use a hydraulic clutch to modulate power to the rear as needed. There are also automatics that use a hydraulic clutch to control a mechanical center differential. They all require pressure lubrication from the pump that is driven by the engine (and an electric motor for start/stop/hybrid models).
The odd one out is the STI - that has an electric clutch that controls a mechanical center differential.