Exar Kun could take Revan, Malak could take Nihilus, Dooku could take Sion, Ulic Qel Droma could take The Exile, and Tulak Hord rips Traya apart.
A lightside team would be tougher, hmmm
How about, NJO Luke holds off Revan for a bit, Yoda takes Traya, Mace takes The Exile, Lord Hoth takes Nihilus and Obi Wan takes Sion. Then they help Luke with Revan. Idk though, the second team would have a very tough time, but my dark side team would wipe the floor with them.