Force - Luke wins, but barely, to be honest. I can even be persuaded to say it can go either way. Kun is capable of some resistance on his own, with Naga's aid and Ludo's small support they can very well win, especially given the diversity of Ancient's skills, quite honestly something on par with Luke. In a Force only fight, where you have one legit guy offering resistance and two guys with ****ed up Sorcery abilities, anything is possible. Naga and Ludo can come up with something sick while Kun does his best to survive the beating, for instance.
Sabers - Luke wins everytime. Ludo is close to nonfactor and Naga perishes like Maul against Palpatine. Kun doesn't hold a candle on his own.
All out - adding in lightsaber combat prevents Naga and Ludo from going nuts with alchemy and what we have here is a repetition of the sabers only fight, but taking longer.
I'd like to know how Luke isn't stomping someone who can't do any damage to him - neither with his lightsaber, nor his Force powers - and can just be blitzed.
Well you'd have a point, if none of those 3 are doing any damage to him. Since that doesn't appear to be the case in any scenario, your point is moot.