I'm experimenting with the "counter team" but I don't think there are enough countering characters of good quality to make it viable at this time. Kylo's is situational, and ironically, only works well when the other team has counterattackers. Dooku's is of course great and Fives is pretty good too. But it's still really easy to just avoid these guys and focus them down one at a time. A counter team is only going to be great against a heavy AoE team, and there aren't a lot of those at the moment. Plus, the AoEs generally will do way more damage than the counterattacks... you're better off preventing them than responding to them.
The other natural place for Fives would be an assist team. That's easy with Phasma and a couple of other guys... like IG-86 or GS maybe. I don't have those guys leveled up though so I can't really try it out yet. Here too, a human player is just going to burst down the serious damage guys and simply save Fives for the end.
I am continuing to work on Fives, because he definitely could be useful, but I just don't see a real role for him as yet.