So Team Exploding Cat got about as far as I expected so I'll break down how I felt that each of the characters performed.
Rika: Obvious MVP. Her biggest faults are the lack of revival and lowish damage, but her skillset just has so much synergy with almost any team that it makes up with it. Even then, Deban and Saner can help reduce the need for revival and ID covers for the damage in a number of fights. One of the few characters who works really well with Nall.
Elincia: Kind of around, didn't really feel like a detriment or asset either way. She worked decently with the team, but I think you'd really have to work to get the most out of her. She would probably have a lot of synergy boosting up some iffy status rates though.
Mew: Mew's sort of odd. Exploding on things with Saner's help was pretty cool and Light Screen was really awesome. The status vulnerability sucks though, and some of his buffs are too self focused. Really wishes he had some status options of his own and one or two more skill slots.
Yukiko: Worked surprising well with Rika. Rika can make up for her healing slump in the middle and she can provide very good revival and a bit more of a damage punch that when combined with Rika's MT physical move only needs a bit more MT punch to get up to the 2.5 threshold. I'm not sure how much she needs Elemental Advance, but she's great with it.
Nall: Worked well with Rika, but I suspect he would be kind of mediocre if you didn't splurge on a character like Rika or Nina 1 to help him out.
I've got an idea for a team that could be a real winner, but I'm gonna hold off on posting it a bit.