Both ponies have one week of prep time and they both have all of their overpowered hax abilities and weapons available to them. Neutral Battlefield. No outside help from others is allowed.
 
Starlight has Starswirls scroll and can time travel at will along with her natural magical abilities.
 
Tempest has an unlimited supply of those grenades that turn ponies to stone and she has her Airship along with her natural (explosive) magical abilities and immense physical agility.