OK here's my current setup:
Tiz: Spiritmaster/Performer
Dual Shields, Shield Lore, Helm Lore, Armor Lore, Protect Ally
Agnes: Arcanist/Time Mage
Angelic Ward, Adversity, Pierce M. Defense
Ringabel: Salvemaker/Merchant
Hasten World, Angelic Ward, Attack Item Amp, Speed 10% Up
Edea: Pirate/Dark Knight
Two Handed, Drain Attack Up, Sword Magic Amp, BP Recovery, BP Limit Up
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In battle, Tiz uses Fairy Aid from Spiritmaster on Edea and Love Power on the party to buff attacks up, then My Hero to raise BP for the party on subsequent turns. Fairy Ward is good against bosses that render status effects. His skill setup lets him tank moves and protect allies from single hits. (I have two Blood Shields for him now btw). Reuse Fairy Aid/Love Power/Fairy Ward when they run out of course.
Agnes mainly supports with Reraise from Time Mage on the party, which brings your members back to life automatically if they die. Pierce M. Defense I haven't found use for yet but can be good for random battles, and Arcanist's high int/mind is good. But I've just put my encounters on -100% now since my party is lvl 80-81. Angelic Ward and Adversity are good to keep her alive.
Ringabel uses Low Leverage (amazing skill at no MP/BP cost) to halve MP cost/BP cost/enemy/party damage. The halving of party damage isn't very detrimental, but halving of enemy damage can really help, not to mention halving MP and BP cost for high MP skills like Reraise/Meteor or high BP skills like My Hero. He also uses Widen Area for X-Potions to heal the party when needed and Giant's Draft is great since it doubles party HP (just found out that HP can go above 9999). However, Giant's Draft hasn't been necessary yet since the bosses are easy so far. It helped for Satan though. Reuse Low Leverage when it runs out. He has Speed 10% to go very fast, especially when combined with Hermes Shoes. Hasten World is also very useful for building up BP. Additionally, this high speed helps him use Resurrect efficiently in rare cases when the rest of the party is dead (it resurrects the whole party at no MP or even BP cost I believe).
Edea is my main attacker. I'll first have her Default to raise BP a bit, then next turn I'll use Blood Blade (a weapon) to have a Drain effect active on her attacks as well as Life or Death (raises her attack but she dies in 5 turns). Then I'll Default again to get her BP up to 4 (you can get BP up to 4 with BP Limit Up FYI). The next turn I'll use Rage 4x, which does crazy damage as I've stated before. When she dies, she'll get revived with Reraise. Then I'll try to heal her up with Ringabel, then start her cycle over again. Bosses won't take long to die when she's doing crazy damage. I have Hyper Bracers on her to raise damage btw.
As for grinding, there are ways to get money through the Japanese Mammon that you can steal Elixer from, or the Big Pharma (Merchant skill) trick, but I don't have a JP Mammon and was too lazy to set up a Big Pharma loop. So I just grinded money from this forest type area to the Northwest of Florem. It has a rock structure near it btw. Enemies can give 4k-8k pg. Try to beat these enemies quickly using Crescent Moon or Bomb Fragments and such.
Eventually, you can afford a Golden Egg, which is a Norende item you can get from the Adventurer. It costs 200k. This stops you from gaining EXP/JP but doubles pg gain. So you can make 8k-16k pg per fight. Eventually, you should get 500k to get the Growth Egg, also from Norende, which doubles EXP/JP at the expense of no pg gain. Just equip it and fight these enemies in this area. You'll get EXP/JP pretty fast.
Edit: Oh yeah, Stillness (no damage for allies/enemies for 2 turns) from Spiritmaster can be used while prepping Edea for damage.
I haven't used it much since it hasn't been necessary, but I'll be experimenting. Also, My Hero may not always be necessary when frequently Defaulting with other characters and Hasten World. I'll be trying to Default more with Tiz to see how much damage he can take.
I also haven't been using attack items for Attack Item Amp on Ringabel to be really needed so I'll have to see if I replace that with something else.
And I forgot to mention the Insect Antenna + Dark Matter compounding combo with Salvemaker which makes enemies weak to Dark element attacks, which is what Rage is.