Well...
The 3 guys there are more powerful then the B team, but they're not quite as good as Mace. Depends on how many of them Sidious can ragdoll at once.
Sidious may even be able to take the Saber rounds. He can't blitz them, to be sure, but he's still far faster. And he doesn't have stamina issues.
Sidious can fodderize Darth Maul immediately with TK and Darth Malgus has no feats suggesting he would suffer a better fate. Basically, two of them can be temporarily KO'd whilst Sidious fries Vader. Round two is medium difficulty.
Round one is the hard part. Whilst Trocity is correct concerning Vader's superiority to Mace he forgot one thing. Mace had Vaapad on uber mode which allowed him to defeat Sidious in their duel. Vader doesn't have such an extreme advantage and thus probably doesn't perform as well.
Enraged Maul can put up an above average fight against Sidious in pure sabers, Darth Vader can likely produce the same or better. Malgus is fodder against Sidious level opponents. Sidious being a smart bastard likely uses Malgus as a harmless stop-gap between himself and one of the others before surgically cutting one of them down at which point numbers become irrelevant.
Sidious wins both rounds.