The Flash vs. Thor
Absolutely no PIS/CIS. Flash is at his MAXIMUM potential and Thor is at his normal power levels.
The Flash is absolutely bloodlusted and is more than willing to kill no matter what it takes.
Thor is the same. They will utilize their powers to the fullest.
Flash has an extra stake in it. If he loses, his wife and kids will under go the "Hostel" treatment to be tortured horribly for the rest of eternity.
They fight on a planet that has completely even plane. Nothing but smooth concrete. Nothing else is on the planet. No gophers, no rocks, no boulders. NOTHING.
They have no basic knowledge of each other.
They cannot get outside help from others (i.e. Odin or the JLA)
They stand 20 feet apart from each other.
They are not allowed to leave the planet at all via teleportation, time-traveling, dimensional travel, etc.
Thor is not allowed to reach escape velocity to escape the planet's atmosphere. The maximum height he is allowed to achieve is 500 feet in the air. If passes this line, he automatically loses.
If a competitor destroys the planet to such a level where it becomes unihabitable, than the said competitor automatically loses. (i.e. planetbuster).
They are not allowed to draw power from outside energy/magic/etc. sources. Flash is only allowed the Speed Force while Thor is allowed whatever energies he holds in his hammer.
Debate.