Hmmm... is Rand allowed to channel? Is magic in general allowed? If it is, then end of HOA Vin, the Lord Ruler, end of HOA Sazed and some of the others mentioned would be overkill. May as well bring in Ruin to make sure the job gets done. If not, it becomes a much more difficult fight. Rand can fight without magic, but Vin, the Lord Ruler, and Sazed I'm not so sure about - I think they can, but each seems to rely on their magical abilities more than their pure physical.
Mat. Definitely Mat. His luck can turn the tide, and he's a skilled strategist. Add in the reach provided by his ashandarei and his cool hat...
Perrin, because you can't have Rand and Mat without Perrin. He can smell what the opponents are feeling, and his other senses are just as highly attuned. All three Ta'veren in one place...
Vasher. Knows how to handle a sword, even if it's not his sentient blade. No certain how much use Breath would be, but if can use it, it can't hurt too much.
Aviendha can fight with weapons and without, and is strong in the One Power if channeling is allowed. Having her there, and in potential danger, would make Rand fight harder (is this an all-on-all brawl, or seven individual matches?)
Despite what I said above, I'm gonna pick Vin as well. She's tough, scrappy, and her size could prove an advantage against larger opponents. She's ten times as valuable if she can use Allomancy, but even without I think she's proven herself intelligent, capable, and resourceful.
The last spot is hard to pick... I want to go with another Sanderson original, to make it 3 from Jordan and 3 from Sanderson, but my gut is telling me to go with Gareth Bryne. He's a blademaster, one of the Five Great Captains, and he has the Warder bond enhancing him now. He's experienced, intelligent, and dedicated. The Warder bond is the only thing close to magic he has, and honestly I don't think he'd even need that. Just give him a sword.