Can I move an enemy unit to a battlefield where I have defending units, choose not to select an enemy unit (if none remain), and start a battle with my defending units against the attacking unit I just moved?

Ruling: Yes, this is legal. You can move an enemy unit to a battlefield and if there are no other enemy units there after the move, you would not choose an enemy unit, resulting in a battle starting on that battlefield with your defending units against the attacking unit you just moved.

Nuances:

• If there was a second enemy unit present on that battlefield, you could not choose to not continue resolving the spell - you would be required to select an enemy unit.