__________________ There are no contests in the Art of Peace. A true warrior is invincible because he or she contests with nothing. Defeat means to defeat the mind of contention that we harbor within.
- Morihei Ueshiba
Kyp Durron showed immunity to Force lightning and very strong in use of the Force in general. However, he was so so with lightsaber, so there is fair chance of him taking Kit Fisto role.
Kyle Katarn is combat expert and one of the gretest duelists of his time but I don't know much about his Force defenses. Saba was as great in combat as Katarn, fighting with Barabel viciousness she showed herself superior to Kent Hamner. However, from fight with Welk it is clear that her Force defenses are bad as he was successfully Force pushing and electrocuting her.
Corran Horn wasn't a great fighter, however, he could comfortably absorb energy like Force lightning. There is no direct evidence that he could absorb Force pushes but, if he couldn't, Jensarai would simply subdue him with telekinesis. Also, he could mess up with Palpatine's mind by creating random illusions.
Overall, if they worked as a team or even use mind meld, even DE Palpatine would be at disadvantage.
Other two scenarios are kind of boring.
Imho even as Caedus Jacen has more advantages over Bane. Redeemed Jacen would be something really awesome.
Senate theme would complicate and prolong fight. But I am sure that Luke will not loose his lightsaber because of Force lightning.