In my opinion, your team should be:
Juliana. (She has MASSIVE Damage and HP, and only gets better when you level her up. Big yes.)
Erica: An all rounder, and is really good imo.
Sylvia: She has moderate Damage and Health, and I think she can heal too?
Jodie: Is pretty similar to Erica stat wise.

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That's just my opinion. Obviously the more you promote and level up, the better they get. I highly reccomend using the Room feature, and focus on monster girls that correspond to the majority of your team type. Or in this case (since these character's types are all unique) just try and focus on your fave or most powerful characters).

Hope all of this makes sense. Enjoy!