Team 1 will comfortably win in this contest, it have decisive advantage.
Ventress is almost a non-factor here. She is utterly outgunned and is likely to loose quickly. This would put considerable strain on Team 2.
Marr and Thanaton are easily among the strongest Sith to have ever existed. As I have noted in this thread, these two are foolishly underestimated. Thanaton, in particular, should be able to handle even Vader.
Malgus is definitely better then any member of Team 2, even Vader. He will defeat any opponent he will face. Not to forget that he can unleash Force Maelstrom and/or powerful bursts of anger in the form of screams at will to further strain Team 2 apart from the loss of Ventress.
Emperor's Wrath holds his own as well due to his immortality and exceptional dueling ability. He have killed over a thousand Sith and powerful Jedi (even multiple at times) and stalemated even HoT. Such resume is more then enough to rank him among the greatest of the Lords in history, he certainly is. He should be able to handle any member of Team 2 as well.
I don't see how Team 1 looses.