Struggling with Dadaluma

I brought Edgar, Locke, Gau, and Celes to Zozo, and they're level 14, except 12 for Locke. I think bringing Celes was probably a mistake but since running away from enemies doesn't really work in this patch, the long slog back to Narshe is out of the question. I got most of Gau's available rages, aside from two stragglers that outlasted my patience -- Crawler and Conjurer. I've searched the forum for Dadaluma advice and have seen people suggest Conjurer, which is why I mention that I tried to get it and the relevant formations just never spawned.

So I've got Edgar in the back row spamming Bio Blaster, Locke in the front row with two Butterflies, Gau using Wild Rat, and Celes mostly slinging items. i have ~80 Dried Meats, 20 Red Bulls, and 30 Phoenix Downs. Dadaluma's Spoon and Elbow Drop abilities are just things I can't do anything about, right? Can't mitigate, block, or prevent them -- just hope Elbow Drop misses or wears off, and accept that Spoon will OHKO me. Dadaluma's adds I can take out with Edgar's Bio Blaster (or Gau's Wild Rat if I'm lucky with an all target Bio), but I can't predict when the adds will spawn. Dadaluma has a really powerful regen than I don't think I can prevent, and he seems to just have bottomless HP. When he jumps, I also often lose a character, but not always. So it just seems like a giant war of attrition, and I feel like I'm making progress but eventually Elbow Drop and Spoon hit the wrong targets at the wrong time and at that point I lose my grip on the fight. Each attempt feels like a really long slog. I'm hoping esper levels will increase my survivability, but obviously that doesn't help me with Dadaluma.

Specific questions:

1. Is it possible to predict when Dadaluma's adds will spawn?
2. Can I prevent or remove Dadaluma's regen/haste buffs?
3. How many Phoenix Downs do I need, realistically?
4. Aside from Defending when Dadaluma uses Slim Jim, is there anything I can do to mitigate his offensive abilities?

1. They're on a timer.
2. Dadluma's counter script is complicated and increments depending on what attacks you use against him. Certain attacks will make certain variables increment at different speeds, but none of them can be outright prevented. You are meant to counter Regen with Sap and Haste with Slow (Suplex, if you have it).
3. I personally recommend about 20-ish at all times. YMMV.
4. Better armor? >.>

I'm not really much of an expert, but your team is actually very similar to what I had when I fought him. ( Locke, Edgar, Cyan, Gau.)
Though I ended up at a higher level for sure since I tend to wander around places making sure I get everything, fighting the randoms along the way.

How I dealt with him is I actually had Gau raging Hornet which casts Slow X to keep him slowed, and the slow casts will remove the haste he gets every time he pops a Slim Jim, it's damage from attacks isn't too bad either with 3x damage for it.
With Locke I had him dual-wielding Full Moons from the back-row, it's safer and it still puts out really nice damage with the random throw procs. (Very satisfying for me every time both hits proc.)
If you have the Drill for Edgar that can set sap, which will remove regen in the process so that can help a lot too, otherwise you can also use Gau on Albatross to set sap with Fireball, but that does put him on double duty which can be pretty tricky if you don't know what you're doing.

This is the gear setup I had, though I will first admit that I still did extra GP grinding at this point because I have problems and want to own everything when I can. (But with exp gain turned off so as to not become even more overleveled.)

Oh man, I just beat him after another long attempt. I wish I had realized that Drill set Sap; Bio Blaster was pretty strong but shutting down his regeneration would have made such a difference. My fault for not checking the documentation when I picked up Drill; his other tools seemed essentially the same as in vanilla so I didn't check.

Congrats on killing him. Dadaluma's a bugger.

***

For some post-battle notes, a strategy I like to employ is to actually use the NoiseBlaster to confuse the Brawlers, rather than kill them with BioBlaster. Every attack against Dadaluma will count up his "counterattack meter," but NoiseBlaster isn't an attack, so it bypasses this. Also, his goons will then occasionally hit him, which also bypasses his "counterattack meter." Also also, it gives you a buffer against whenever he calls for more goons.

Downside is that NoiseBlaster lends itself more to a slow, tanking set-up. Drill Dadaluma to set Sap, confuse his goons, and let Sap do a lot of the work while you only use a few big attacks to minimize how many counterattacks you eat. (Having Locke use Healing Shivs is nice for this, though you had Celes at healing).

Also, the next release will be giving Celes a new tool to help her out in Zozo & the Magitek Factory. I wouldn't wait on the next release before I continued playing, nor do I know if or when you'll replay this, but I thought I'd give you the FYI.

Speaking of the Healing Shiv...

Given that I've now unlocked some espers, and given that I have to take Celes to the southern continent, is it worth trying to find a Healing Shiv? I was mugging the appropriate enemies but it's the rare steal so I never managed it. My usual approach to RPGs is to just do my best to grab what I can along the way, and not go out of my way to grind. But I'll grind if I have to. Is the shiv important enough to grind for?

It's not intended to be.

The Shiv, this early in the game, is basically a full heal to one character, but it sacrifices Locke's physical attack. (You can still Mug, but Healing Shiv doesn't have bonus multipliers like Butterfly's "2x damage to humans" or Full Moon's "Randomly Throws for 2x damage"). I think it's actually almost always a full heal on a single target, even later in the game. IMO, it's stupidly powerful for the IMF & remains useful throughout the WoB; part of my opinion being because I'm not a huge fan of Fighter Locke in the WoB, unless I'm going all-in with Kirin levels.

That said, you seem to prefer having Locke hit stuff rather than playing field medic, so it might not suit your playstyle. It's not totally necessary for the Southern Continent - plenty of the other veterans here don't bother with it. You could maybe give a few more attempts to snag it, and if that fails, just continue the game.

You already got good answers, but here's another for ya. I recenlty beat him with everyone at lvl 10.

Locke - BACK row with Butterfly and a projectile. (Butterfly is x2 damage, so in the back row, it's basically a front row attack for a normal weapon.
Edgar - The one guy you always bring, and can pretty much never fuck up with. Stick him in the back and Bio Blast for days. Use Drill if you're lacking Sap damage (Very important)
Gau - Conjurer is well worth is, but once everybody is rerised, he's basically dead (speedy) weight, so either Green Cherry him or just skip that all together and stick with Wild Rat (Always get massive damage, often, and have a decent chance to set Poison.

Shadow - back row, x2 Butterfly, spend most of your time tossing Smoke Bombs (Buy them in Jidoor) and you're safe from A TON of damage.

Other people:

Celes - The least important imo, as her only major contribution (Cure) can be replaced quite effectively with items if you stock up well. (Shadows speed makes up for less healing power of Dried Meats)
Cyan - Overkill, but if you bring him, Dispatch for days, and don't forget to Empowerer rather than heal, as he'll almost always replenish to full, and it saves you items + it sets Sap.
Sabin - Pummel for Sap, Suplex for Slow.


Extra tips:

You have Locke, so steal the crap out of Slim Jims for Haste/regen, as they are easily the two best buffs, and unavailable either way. Also helps reduce healing.
DEFEND! I know defend is very situational, but if you're well healed while Dadaluma is in the air, you have nothing else better to do. This ensures that even frail fighters like Shadow can survive a direct hit (AT LEVEL 10!)

Note: Very tired, so I missed a couple of things you said, like Defend + Slim Jim.

This fight is definitely hard, but if you setup right, it's only moderate difficulty. (Lost but once with above setup)