New party with Kain, Golbez, Edward, Gekkou, Izayoi.
Spiral Blow (Golbez+Kain) is the normal damage dealt by Kain and Golbez plus 50% (will need Limit Ring to take advantage of, but ultimately not worth it). It is certainly most affected by the moon.
It would be nice if someone would want me to look into certain combine-able skills and see how the math comes out... (please, good combinations requested too).
Phantom Lightflies healing is literally the combined HP loss of both Izayoi+Gekkou plus a 25% bonus, then split to all the characters. So if Izayoi+Gekkou has lost 5000 HP combined, the healing is boosted to 6250 from the bonus, then split to the # of characters that are alive (so, minimum 2, max of 5 of course). It is possible to have Izayoi+Gekkou to be self sustaining with probably one other character.
Final party will be constructed with Edge, Rydia, Harley, Tsuiknowa, Zangetsu... having virtually no anti-machine power.

For clarification, these parties are meant to grind against the machines to level 75 for all characters at a minimum... completed that, although the dolls have not been touched at all.
I subbed out Harley ASAP and put in Luca... that should allow for some decent combos.
Mecha-Kite allows Zangetsu to deal an additional 50% damage from his normal "Jump" (Human Kite). There is a 50% damage bonus if the target is floating (weak vs Wind). Skills is definitely affected by the special attack moon phases.
Gale Twin Break.. I don't know what to make of it other than a massive "Jump" on one target and the other targets seem to get 1/8 to 1/10 the damage of the major target... it sucks late game for sure.
Wild Moon seems to simply average the two's attack power or damage (Edge+Tsukinowa) and hits everyone with that. Useless or kinda weak when the target is solo.
Flare Tornado with the Limit Ring only seems to deal 12-15k worth of damage (when unaffected by the moon phase) and is affected by Black Magic and Special Attack moon phases. Damage is split between targets (which is fine when you don't have the Limit Ring) - great for 15MP.
Inferno is similar to Flare Tornado in the moon phases bit. However, damage is not split between targets (it's really just a Firaga that isn't affected by split damage in some ways).
At this point, Lightning Brain Buster (Luca+Rydia) seems to allow Luca to do 2 times the damage that she would normally do (not factoring in elemental weakness) and it doesn't factor in the weapon's elemental or racial properties. I assume the damage is really scaled a lot by Rydia's INT....
Broken Heart, despite not being a Wind elemental attack through the bow+arrow, is definitely affected by the Attack Moon phase... it's damage is Edge+Rydia's normal attack + 50% bonus (I think) and damage hits all enemies equally. No bonus for a solo target.
Right now, I'm trying to construct a group for the battle with Bahamut...

Alright, I'll go with Team Magi (Rosa, Rydia, Palom, Porom, Leonora). I couldn't quite find a great group to single target band with (as in a cap breaking one) and one that would involve Rydia but that was never meant to me.
Infinity - Obviously affected by White and Black magic moon phases... the worst phase is the one that neuters White Magic outright (boosts special commands).. and the best moon is one that boosts Black Magic outright... which cripples physicals, which is perfect. The phase the boosts White Magic and cripples Black Magic will still boost Infinity (since you have a 3 to 2 ratio of White Magic to Black Magic in the attack).
White Magic Crippled: 32k damage
Normal: 40k damage
White Magic Boost, Black Magic Crippled: 48-50k damage
Black Magic Boosted: 52k damage
Front line characters would involve Rosa and Palom (at least Palom with the Adamant Shield, Rosa with a bow+arrow is fine). Rosa has the most HP of the bunch, followed by Palom.
Ideally, black magic boosted is better... for various reasons... I will list why in a bit...
The other bands that of relevance:
Tri-Disaster (20MP - Palom, Leonora, Rydia) - most affected by the moon... 21k @ the moon phase, 18k w/o the black magic boost... anything else cripples it - split damage applied, so to benefit, you will need the Limit Ring (primarily on Rydia IMO, as you'll see why) - potential can be reached if you can somehow boost Leonora's INT stat since she is the worst of the bunch.... and only for 60MP total...
Thunderstorm (Palom+Rydia) - didn't use enough - not really powerful...
Pure White Magic - explained earlier - probably optimal for this group, note that Leonora is the first to have MP problems of the group in general...
Holy Ray (50MP - Porom, Rosa) - it's dual Holy, with split damage... probably better for massive monster killing instead of Limit Ring usage... almost 20k w/o White Magic moon boosting...
Holy Burst (55MP - Rosa, Rydia) - imagine what Holy+Flare can do together... same as Holy Ray, and powered by different aspects so the White Magic boost+Black Magic nerf shouldn't affect this negatively (just the White Magic nerf probably would)... it's better than Holy Ray since Flare uses a higher base damage... but I'm unsure if that's actually being used (it seemed to work better than Holy Ray overall)... split damage a small negative and Limit Ring required to maximize potential... 20k easy...
Sprite Bred (40MP - Porom, Leonora) - poor man's version of Holy Ray for one target... it's technically a waste of a Limit Ring because Leonora's SPR is not at the same level as Porom's (let alone Rosa) despite it being Leonora's better stat... you are better off using Leonora for Dual Holy through Twincast and Twin Stars for keeping MP usage in check and deal effectively the same amount of damage as this band with the Limit Ring... got 15k or so damage from it... which was very disappointing...
Twincast (40MP - Palom, Porom) - as explained earlier, the Limit Ring would be more useful if you got dual "Flare" being cast as that would hit 20k easily...
I would like to mention it is very difficult trying to juggle all the equipment you would need to move around, as the best armors for Black and White mages are taken first.. so make sure those who get the good stuff really benefit from it.
Rydia with the Limit Ring is most beneficial here, since Holy Burst and Tri-Disaster can be most beneficial in a damage/MP conscious crowd. While Tri-Disaster can be run, Rosa+Porom can use Holy Ray or do other stuff...
Alternatively, you could run Holy Burst with Twincast with Lenora to do other work... also Holy Burst and Sprite Bred with Palom for the extra damage through Flare or Quake....

Fought Bahamut... it wasn't too bad.
The good: 3 White Mages with Arise is better than none.
The bad: Fought this battle when Black Magic was favored... especially when that's primarily what the Mysterious Girl relies on... and the only White Magic I've seen to date is Haste (Holy isn't in their repertoire?)
So, the leadoff Meteor pretty much killed everyone outside of Rosa, which was great. Most of the time was spent doing the following:
Rosa
Primary: Reviving the White Mage that has Dualcast (Porom or Leonora), Revive Porom if neither has Dualcast (Porom has more HP)
Secondary: Healing
Tertiary: Holy
Leonora
Primary: Reviving/Healing Rosa first, Dualcast Revive on others (if applicable)
Secondary: Dualcast Curaja and Float to avoid Quake, otherwise Healing
Tertiary (if applicable): Dualcast Holy
Porom (same as Lenora)
Primary: "
Secondary: "
Tertiary (if applicable): "
Palom
Primary: Spider Silk (as a counter to Haste or no-Haste)
Secondary: Flare (Dualcast Flare if applicable)
Rydia
Primary: Spider Silk (same as Palom)
Secondary: Flare
Dualcast for Porom or Leonora can make certain battles more forgiving. I guess this is one of them. Black Hole doesn't affect Bahamut (whether under Haste or Slow), so that's good news.
Note: The real trick to Deathmasks, is using the multi-Reflect to cast (preferably Dualcast) Slow. That makes your life infinitely easier. I didn't really abuse that in regular FF4, whether it was the GBA port (specifically the Euro version) and the PSP port. This is great to screw with their spell timing as they will occasionally hurt themselves with their spells towards the end of their spell sequences. This is also great when Slow stacks to a degree.