The only composition you really need to worry about is a mirror match. Darth Revan absolutely destroys everything else. I guess without Malak, Padme might be an issue; not sure as I haven't fought a fully zeta'd and arena-modded Padme yet. Regardless, you'll destroy other teams so soundly that for now, you can safely plan strictly around mirror matches without worrying about other comps.
For that reason, Assassin is right out, as the tweak to Malak that knocked out EP as a counter also removed her most valuable asset, the ability to grant TM to the whole squad. So Trooper/Marauder are gonna be your go-tos for a full SE team. As someone else already mentioned, Trooper is all but required unless you have the absolute fastest DR on your entire shard. Otherwise, a faster DR will open with Insanity on yours and fear your whole team, and then you've basically already lost.
Other characters that sneak their way onto DR squads are GM Yoda, Thrawn, and Unmasked Kylo with his pretaunt zeta. These are all ways of compensating for shortfalls on your SE guys - GMY helps against a faster BSF by using Tenacity Up to block CBM, KRU can eat Life Drain due to his near-immunity to %health effects, and Thrawn can fracture Trooper so that you can nuke down BSF without him yanking your focus away with his auto taunt. I think that's what Thrawn is for, anyway. I've never been one of these "solve everything with an ultra fast Thrawn" fanboys, mainly because I don't have the speed mods for it.