I wouldn't bet on it right now.
I think all-out Urek probably wins Mid-Diff against either of them individually. Urek would for the most part dominate, but he's probably getting put into some tricky spots that result in inevitably some form of damage (even if not severe).
2v1 would be tough, especially considering Gustang and Traumerei have been long-time friends who climbed together, know each other's abilities, and are used to team fighting. Their synergy is probably very good. They're very smart and have a fuckton of hax on top of it.
For now, betting on the duo. We might have an answer for this soon, actually.