Eternal Sonata

Just like the 2nd time. You should go to the Aria Temple to level up if you are still having trouble.

As a guideline, I was level 29 with March, 30 with Allegretto and Viola.

For strategy, I used March's Aurora Curtain everytime with Allegretto near by to boost up his Sun Slash and kept them in the light. I also had the Brilliant Brooch on Viola to ensure that should could use Heal Arrow each turn after attacking as many times as she could from as far away as possible.

Lastly, kill the two lesser pirates first, as they can heal and revive just like before.

Use Frederic seriously. As he has a great healing spell called Spirits Pathway. If you hit the triangle button fast enough, you can use it three times in a turn. Besides Frederic, I was using Salsa and March. March's Aurora Curtain can be a real life saver sometimes, since it gurrantee 0 HP loss on the first enemy hit and 0 HP loss on non targeted characters. I was on level 32 when I fought Dolce. Just take out her two bodyguards first, then followed by her. Frederick should only be used as the healer, nothing else. If done correctly, you probably don't even need to move Frederic an inch! Good luck!

Level up good, about the 30's , i used Frederic, Viola, Allegretto
Viola can make or break your party, my startegy was to beat the slaves first then focus on the captin, just you make Allegretto + Frederic close to Dolce and attack her.
make Viola attack dolce from a distance using her normal attack <-------
and try to be far away from dolce and attack her cause viola's attack power varies depending on the distance :)

Tihs fight is actually easy if you have a good strategy, and are fast at blocking.

For this fight, I used...
Polka (Level 31)
Equipment: Saffron Parasol - Cloud Cape - Brilliant Brooch - Spell Book
Skills: Earth Heal/Orange Cure

March (Level 34)
Equipment: Night Watcher - Crystal Suit - Pocket Watch - Speed Shoes
Skills: Super Nova/Full-Moon Bind // Aurora Curtain/Eclipse Gaze

Chopin (Level 34)
Equipment: Gold Baton - Bird Cloak - Spirit Arrowhead - Power Ring
Skills: Coup De Grace/Orzel Bialy // Mirage Blow/Coup de Jarnac

March/Chopin built echoes easily enough; the two subordinates should go down in one special attack; at most two. You should have no trouble after they are gone if you have Polka healing with Earth Heal while Chopin and March fight Dolce. Full-Moon Bind often puts her into stop, reducing damage dealt, and Chopin's Gold Baton allows him a lot more extra damage. Just make sure the two attackers are close to one another -- close enough that Dolce can't slip through the gap between -- and she'll continue to hit you from the front, allowing you to block her attacks. As a rule of thumb, allow half a character's space between the two -- Dolce will try to slip through, occasionally, but she can't.
If you're brave enough to keep Chopin's back to Dolce, you can use his Coup de Jarnac on one of her minions for fast damage, instead of starting off focusing on just the henchmen.