When playing Showstopper, can other units move from base together with the selected unit, or must it move alone?

Ruling: The unit using Showstopper must move alone and cannot be combined with other units moving from base.

Nuances:

• Both Showstopper and standard moves are base speed
• You cannot activate Showstopper at the same time as standard moves
• Multiple standard moves can be activated simultaneously if they have the same destination, but standard moves cannot be combined with other move effects like Showstopper