FORCE ONLY
1. Kas'im - Jacen borderline stomps.
2. Kit Fisto - as above.
3. Kyle Katarn - Jacen wins everytime, but Kyle puts up some resistance, but not a very good one.
4. Mara Jade Skywalker - the same.
5. Obi-Wan Kenobi - the same.
6. Jaina Solo - Jacen everytime, but Jaina puts up a great fight.
7. Mace Windu - honestly, Jacen may lose sometimes; Mace eclipses his NJO iteration in few things, but still Jacen for the majority.
8. Freedon Nadd - oh, NJO Jacen loses here, definitely. DNT Jacen would win, though.
9. Kyp Durron - I don't see any version of Jacen superior to Kyp in Force only.
10. Darth Vader - Vader in a good fight.
Boss: Exar Kun - Exar, definitely.
In bonus - he can get through Mace easier, but he still stops at Nadd.
ALL OUT
1. Kas'im - Jacen borderline stomps.
2. Kit Fisto - Jacen wins easily.
3. Kyle Katarn - Jacen wins. Good resistance from Kyle on every front, not much of a change.
4. Mara Jade Skywalker - as above.
5. Obi-Wan Kenobi - Jacen wins in a grueling fight, probably everytime, and each time thanks to the Force edge; they're very close saber-wise.
6. Jaina Solo - Jacen very, very narrowly.
7. Mace Windu - Jacen loses. Too inferior as a combatant, and he can't close that gap with Force power - he won't have the ability to go for a prolonged focus on Force assault.
8. Freedon Nadd - Jacen wins. Freedon is too inferior as a combatant, although Nadd's Force superiority will give him hell, but I doubt Freedon can go for a full Force onslaught mid-combat against his lightsaber superior.
9. Kyp Durron - Jacen wins; too good of a swordsmen compared to Kyp.
10. Darth Vader - Jacen falls. Inferior in everything.
Boss: Exar Kun - Jacen falls. Equal as a swordsman, or slightly superior, but too large disparity in the Force.
In bonus - he has more chances with Mace and may edge out Vader and Exar for a minority.