I am so glad the story party for EO2U in terms of class synergy is so much more fun/unique then in EOU. Although I do find Flavio to be a bit dead weight. Maybe if I change him to a gunner. But I also made the mistake of not reading how Efficiency works in this game compared to EOU and made the mistake of investing points to get it.
Bertrand is standard Protector.
Chloe seems like the healer but she goes about it in such a unique way (and praise the sun that she isn't a medic) and she seems like she can do other good stuff too. I've actually been tempted to try putting her in the front row instead of Arianna but Arianna's Link Order feels like it has too good of a synergy with Hero's Sabre skills, then again it also feels like it might take away from her doing other things.
Hero is really unique and is obviously a damage dealer with a focus on physical element attacks.
Flavio is just kinda.... there lol.
Arianna is support though she has some key differences from EO3 Prince/Princess and she feels a bit more offensive. Still tempted to switch her to back-row support though. Can't decided.
I decided to play story mode this time since I really like the party.
Anyways, Flavio helps Chloe, thanks to the Survivalists now having a few ailment inflicting arrows. It probably wouldn't hurt the party too much if you changed Flavio's class because of the changes to the War Magus. The War Magus can still do it's thing without someone else hitting enemies with ailments thanks to Random Disease and their Force Boost.
Right now, Arianna tends to be my main healer because of the healing when casting buffs as well as Protect Order. Chloe's heals are nice if I'm in a tight spot since they're guarantied to heal a some at the start of the turn. The Fafnir Knight deals explosive damage, and thanks to Arianna's Negotiate skill I can build force meter up quickly. Flavio is either inflicting ailments or getting some damage with Multi-shot, while Bertrand is usually falling back on grimoire skills for damage unless I really need the extra defense.
I may change some of the classes for the story mode party later, but I'll hold off on it for now. I'm actually looking forward to experimenting with grimoires this time, they've been improved so much. I have some ideas for my current party, I just need to wait for the skills I want to show up in grimoire trading.