Major Vaughan should be his own leader because Captain Cutter already has Jerome as his Hero so Major Vaughan can have Boomerang company as his hero without having Spartan Jerome being removed.
So if Major Vaughan ever became a leader, a good leader power for him would be a trio turret drop, which would have one anti-infantry turret, one anti-vehicle turret, and one anti-air turret.
A good unit for him would be a wasp or hawk.