Feel stuck. Need help.

I started playing when tronys banner was just about to end and I'm currently stuck in the beginning of chapter 14 and don't know how to make my nikkes stronger from here nor do I know any good teams to try out. What should I do from here? Any help would be wonderful.

I started playing when tronys banner was just about to end and I'm currently stuck in the beginning of chapter 14 and don't know how to make my nikkes stronger from here nor do I know any good teams to try out. What should I do from here? Any help would be wonderful.