I've included details about each fight/Verse in the description, please read for more details:
Verse 1: There's three phases to this fight, and rocket punches make short work of all of them by stunlocking.
Phase 1 involves rushing to each leg and then attacking it. I do a double jump before attacking to be at the right height. The missiles here are tricky and caused MANY more restarts than I'd care to admit, because I kept forgetting that second volley was incoming. 2 legs, then dodging the water bites, easy magic recharge by parrying the leaping dive attack, then 2 more legs.
Phase 2 involves punching Sapientia right in the face. If you move far enough away you can actually try and bait fireball attacks which are easy to deal with, or he might do a charging bite attack to close in close to you. With a bit of luck we get some good stunlocking hits in.
Phase 3 is pretty easy. Tetsuzanko with Shuraba or Heel Stomp seems to hit him easily at the start, and you can easily wreck half of his remaining health before approaching him if not more. Then just stay back at fireball range (as the bites are much harder to dodge) and parry the fireballs between attacks.
---
This Bayonetta playthrough features the secret character "Little King Zero", who is unlockable by clearing the bonus chapter "Lost Chapter: Angel Slayer". Little King Zero is the hardest character in the game to get Pure Platinums due to his innately equipped Infernal Communicator interfering with the use of both Pulley's Butterfly and Sergey's Lover. His minor advantage of very slightly faster running speed and slightly improved magic gain per hit (mostly noticeable when using Scarborough Fair, Handguns, or Bazillions) do not make up for these disadvantages.
This playthrough gets a Pure Platinum (no damage taken in combat, Platinum rank time and combo on every fight) on each chapter while showcasing all the cutscenes as Little King Zero, without ever resorting to the checkpoint restart exploit. Most playthroughs on KZfaq resort to this exploit, where you can immediately pause the game, select Quit to Title Screen, and then Continue to restart any fight where you get hit, or if you're worried your combo score or time are too low to get Platinum. It's easy to spot the jump cuts in Pure Platinum runs where players resort to this exploit before difficult fights. It's especially weird when they deliberately avoid the use of specific weapons or accessories (usually Pulley's Butterfly) in order to look hardcore, but then resort to this incredibly abusable exploit to get their Pure Platinums, which essentially removes most of the stress or tension from having to avoid taking damage while nailing combo scores and time in each fight.
If you can just restart any fight you fail, rather than having to restart the entire chapter, it's far less challenging to Pure Platinum the entire chapter. All it takes is to retry the fight over and over until you get through it without taking damage (and hopefully get Platinum combo score and time) then use video editing to cut out the failed attempts. The people who use this exploit to get Pure Platinums often won't mention it explicitly in their video description, and you have to figure it out yourself based on the presence of jump cuts in the chapter. The worst part is this exploit is useless for teaching you consistent combat strategies. Lost Chapter: Angel Slayer doesn't allow for mid-chapter restarts, hence why players who resort to this exploit to get their medal screens full of Pure Platinums tend to have trouble with this endurance chapter. The only other player I know of who has recorded a Pure Platinum playthrough of NSIC without using the Continue Exploit is a highly skilled Japanese player by the name of "tomatyesc", who also has multiple recorded Pure Platinum runs of Lost Chapter: Angel Slayer: / tomatyesc