odd, I never had any problems at all with the game after my first run. None of my mains even died, and I didn't use a single item until my 4th run where i was just getting sick of the obscene hp levels of the final bosses, so i used like, 4 or 5 red mushrooms and cayenne to quickly kill them with dual attacks and combos. I also focused on using the stat boosting equips. After the 2nd run, i avoided all monster fights after chapter 3 using arc, so i think my usual level was around 9-11. Stat boosting gear helps out quite a bit, i'm pretty sure i could've done with less agi or def on my runs.
My most used party was cliff, sheryl, lucy.
I found mena to be useless, and at a basic level she's weaker than all the chars in stats and whatever invisible stat counter they have. Aoi's good but i didnt' get much use out of her skills. Kitty was the same, and she has such low hp that she has to be watched like a hawk. Her skills are pretty useless, except for her fire attack, which is actually pretty good. She also dodges a lot, but i didn't find her useful unless i gave her the hustle item.
i think i put quick items on cliff and sheryl, shield on sheryl and lucy, guts and hustle on lucy. I adjusted their stats accordingly, with cliff favoring def, then atk, then agi, then will, then life. Sheryl i favored def, will, atk, agi (i pumped this up when i first got her however to catch up with the other two), then life, and lucy was agi, atk, def, will, life. I think putting will or life past the halfway point is pointless, and i don't think you get any extra hp for life points if you don't level after you put them in so if you're gonna get life, put it in early.
Putting lucy at the end and attacking with lightning does like 500dmg, plus sheryl's aoe is good, cliff's just there for dual attacks and to setup the combo order. In case anybody doesn't know the combo orders yet,
Cliff > mena/sheryl > lucy > aoi/kitty > loop. I found it easier to just remember that instead of trying to figure out their elements early on. Course after i got all their skills, i figured cliff was earth, mena/sheryl ice, lucy wind, aoi/kitty fire. But I'm not sure if mena or aoi have any skills that indicate their element, and i didn't figure out an easier way of learning their elements.
For the wisor boss when he has his shadows, the shadows i think, do significantly less damage. I'm also not sure what exactly or how exactly it was done but after my first run, with the shield equips, i rarely saw damage over 20 for my chars. My first run i maxed out attack first, and that's probably what made it harder, but i also got the feeling that i got way way more stat points on later playthroughs than my first. I think i was level 17 on my first playthrough and i only maxed 1 stat for each char, and after that i was maxing out 2 stats on chars who were level 4.