I only play chars i like. When I dont play AMK/Lars (mains) I usually mix up one I know better and one I'm not that good with to make up for it. I also try to put them together so Tag assault combos work as good as possible ^^. I never cared about how much the chars like each other
I team up Kuni with Asuka for most parts, also tried Asuka and Lili, Jin and Jun, Jun and Asuka, Lili and Kuni, Jin and Lili, Jin and Asuka or Jun and Lili.
I have absolutely no idea how "well they work together", all I care is to have fun playing the characters. Whether some pro is going to tell me they are terrible or great for each is not going to change the way I like any characters in particular.
I main Asuka with Leo, because i like them, but apparently people say they are a good team. I also play Michelle , and Zafina with one of my mains. Im gonna try to get good with Lili next to add her in.