If someone finds the answer to consistently beating TIE swarms, he or she will probably handily win the World Championships I'd guess.
As it stands, nothing seems particularly good against TIE swarm in my experience. In fact, I can't think of any anecdotal evidence of anyone on the boards claiming to have beaten an 8 TIE swarm as Rebels, despite the question being thrown out there a few times (I suspect the vast majority of posters haven't ever played as/against the true swarm, since most local and home groups probably don't have enough TIEs).
As it stands, nothing seems particularly good against TIE swarm in my experience. In fact, I can't think of any anecdotal evidence of anyone on the boards claiming to have beaten an 8 TIE swarm as Rebels, despite the question being thrown out there a few times (I suspect the vast majority of posters haven't ever played as/against the true swarm, since most local and home groups probably don't have enough TIEs).