You can flat tow a Jeep Grand Cherokee, but only if it has low four-wheel-drive mode with Quadra-Trac II technology. This is only available on select Grand Cherokee models and trims made in 2000 or later. This model can be flat towed because it has a neutral position in the transfer case, thus avoiding damage to the drivetrain.
Just make sure to put the car in neutral and select 4-LO Range before you attempt to flat tow the Grand Cherokee. Failure to do so can cause catastrophic damage to the drivetrain of the vehicle and void its warranty.