Done at 7 or 8.
1 and 2 are barely fights. 3 he could probably TK one of them out and finish off the other, but it's a good fight. 4 is a decent fight but Dooku enevitably has no chance. 5 could be a good fight but only if Jinn press' the attack immediately while Kenobi gives support. Still a win for Vader though. 6 has the potential to beat Vader, however his TK could overwhelm Fisto, which would give him the time to take out Windu. Yoda is tough, but I think Vader could possibly beat him. Sidious is a lost cause, too much of a power gap.
Re: Darth Vader runs a guantlet
Loses at 6, five will be tough he will lose the saber fight but win the force and I think he would take the all-out against Dooku. Vader Vs Mace is close but I guess Fisto could add the extra help for Mace to win although Vader could proabably easily takecare of Fisto with the force. He def loses at 7.