Dantes + double Skadi
I think the current meta to 3 turn in JP is double Skadi, NP2 Dantes, and MLB Kscope or so I've heard. Is that correct? Also, are there alternatives to this, as it seems this setup is in whale territory. E.g Arts comps or Merlin memes.
Probably not to that degree. Unless you swap in some Skadi-level quick buff or NP gain buff or super overkill or against enemies like casters -probably a few of these in combination to make up for that.
With double skadi he will be able to reliably charge up his NP enough in almost all stages for 3 turns (with 50% extra Skadi charge x 2) while having that insane AOE damage - also retaining extra swap for emergencies. Others can work but with less reliability. Just think of that team comp as manifestation of whale's privilege to be brainless.
Double Skadi is mandatory to fire three consecutive NPs consistently, you can't do it otherwise. Another thing to mention, if you have Double Skadi and a Waver you can fire three times with any character with 50% NP Charge and MLB Kaleidoscope (number of enemies and overkill hits don't matter)...Basically Astolfo, he has 50% charge and he can use the Quick buffs from the Skadis to increase his damage to absurd levels.
MLB Kaleidoscope is preferable, its importance depends of the damage dealer. If you are using Dantes you may have some space to insert a 20% NP charge through Mystic Code (Hogwarts uniform or Plug Suit) while with MLB Kaleidoscope you can use the Mystic Code Support to increase damage even further beyond. If you are using Zerkerlot, you can't fire three times consistently without MLB Kaleidoscope because he needs that Mystic Code support to be consistent (Fragments of 2004 or plug suit NP gain buff).
NP2 is advisable because increases the damage by a fuckton and more damage means more overkill hits too (smoother cycles). NP1 can be good enough sometimes, NP2 may be required for some stages.