NJO..
Revan imo outmatches Sidious and i'm not sure about him VS Luke, but Malak won't stand against Luke... He will fall, meaning that Revan even if he defeats Sidious will still have to fight NJO Luke who just had a less dangerous fight and who will be more fit at this time...
Also NJO Luke can probably take care of Malak before Revan takes care of Sidious meaning two against one, meaning Revan dies...
Actually, if you want to get into that, then Luke and Sidious would begin fighting immediately. If we're talking Darth Revan (which I'd assume since he and Malak are on the same team), then the three Sith would probably gang up on Luke; not even NJO Luke, from all I've heard of him, could withstand that. With Luke gone, Revan and Malak go against Sids and Sid won't be able to stand against that.
So if we're going to get technical about it, Revan/Malak could win this.
If not, then Luke and Sids. Malak is the weak link. Give Revan someone like Yoda and that'll make this one of those planet destroying fights.