Well, you'll have Odan, Vodo, and Nomi running around, cutting people off from the Force and WTFpwning them. You'll have Luke, Yoda, Mace, Kyp, Ulic, Jacen, Thon, Revan (?), and dozens of other recognized pwnagat0rs slaughtering Sith by the hundreds, thousands, and then the're'll be all those millions upon millions of other Padawans, Knights, and Masters engaging and mobbing the severely outnumbered Sith. I doubt that Sadow will get the necessary time and focus to create his illusions, and with so many powerful Jedi about, even Ragnos is going down. Jedi Order winz!
On the other hand, you have people like Kun and Sadow going Kamehameha all over the place, Ragnos zapping the hell out of people with that wand, Nihilus draining, Traya instakilling, Revan/Hord(?)/Kun saber pwning, and little Sidious sitting in the corner cooking up a huge Force Storm.
The Jedi probably win, but no planet can survive this.
The Jedi may have the numerical advantage (which is highly questionable, given that the Ancient Sith were an entire civilization and will include the Sith people), but the forces of the Dark Side have the offensive power advantage. Either they all huddle up a la Bane's force storm and destroy them en masse or they use their own individual super weapons.