I have 3 teams as well(leader first).
Magress, Alice, Kikuri x3 - Pretty self explanatory.
Felneus, Douglas (x2), Serin, Tree - The Tree uses Refined gem. I main the Tree in this party because statuses are about the only thing out there that kill endless BB spam.
Michele, Alice, Douglas, Felneus, Rashil - Just because I like the concept of the Rainbow team.
I just got my second Douglas up there this week. I mix and match units on occasion for special targets, in addition to the above I have Karl, Seria, Elimo, a 4th Kikuri, Lancia, and 2 more Trees. Having 3 trees each with a Refined Gem is pretty much how I beat Karl without any Thunder units.