You'd need 8 players.
First round: 4 battles. Winners proceed to round 2
Second round: 2 battles. Winners proceed to finals
Finals: Winner gets co
Tell me how that works with 6 players :P
First round- 2 battles, the fastest people to complete the challenge get auto seeded to round 2
Second round- 2 battles, Players who won in the first round fight the auto seeded players
Finals- Winners of second round fight for co