1. Master Chief (with all weapons from Halo 5, but only one clip of ammo for each)
2. Doomguy (with all weapons from Doom 2016)
3. Darth Vader (Legends and Canon feats)
4. The Ur Didact
5. Samus Aran (base gear only)
6. Darth Sidious (Legends and Canon feats)
7. One Time War era Dalek
Dragonborn has full knowledge of The Didact, Samus, Sidious, and the Dalek.
All fights take place on the Throat of the World in Skyrim.
Dragonborn has a full set of daedric armor and all dragonbone weapons, with unlimited arrows. All spells and shouts can be used. Dragons can only be used as a distraction and can not fight for the Dragonborn. Slow Time can be used only if the fight is too one sided. Lore Dragonborn.
My knowledge of most of these characters is limited, so let me know if the order should be changed.