Jeth, Haazen, and Desann are rather good.
Jeth battle-meditates everyone and provides force offense. Desann is a strong duelist, Haazen has his sith artifacts to defend himself from Malgus's attacks, and Sha'a Gi dies like a chump if he gets engaged.
I don't think it'll be easy however it goes- Arca's a fairly famed Jedi, Haazen's artifacts give him a nice advantage and I'm not even sure what it takes to overwhelm them, and Desann was a skilled student of Luke's.