Been a bit since I messed with LoC (or the game honestly, been taking a break before going back to it for either a ng+ or fresh Ilias run since I did Alice first), but Weak to Pleasure did work on the people it was expected to, the problem usually became them adding a way for the boss to become immune to pleasure so you couldn't keep running that strategy forever (see LoC Granberia for example).
Death Claw on the gravity pleasure build (and I at least think this is just the term used, since the ability makes all hits pleasure damage when it's the most effective choice and the gravity part is really referring to percent damage but it takes longer to say/type that) is a great approach, but eventually runs into miss problems, especially later on. I haven't ventured terribly deep (just enough to get all the LoC superbosses done for story purposes), but from what I've heard you end up switching to mass buffs and multi-hit abilities and really going all in on shields because everything eventually one-shots you, so you aren't allowed to ever get hit by a skill ever again. You'd probably need to talk to some of the few people who did push that far though for more info there.
Yea, the only issue remains the hits missing, although Death Claw at least does not have an inherent chance to miss (unlike the Gravity skills from Time Magic, that have either 75% or 50% chance to miss on their own, without factoring in the other Hit Chances). One way to compensate for that would be to buff Hit rate (there are a couple of ways to do it, from what I remember, I was using a Sing skill to buff the Hit rate by about 200% or something huge), and another is to find specific secret equipment or Gems that offer a Sure Hit passive (although I'm not sure if those currently exist for Sorcery skills, or if Death Claw can Crit, to have Sure Hit on Crits work for it). Even on enemies with resistances to both Pleasure and the Chaos element employed by Death Claw (both Death Claw and the Gravity skills use the hidden Chaos elements, but Death Claw uses a different one from the Gravity skills, thus being good to alternate between them when one of them becomes inneficient against a particular enemy), Death Claw still deals damage based on Max HP, meaning that, inevitably, in a certain, linear, number of hits, the enemy will go down, regardless of their Max HP or Current HP values (and so far, no enemy was fully nullifying those attacks, so it's always doable to a certain degree).
As for the other strats you mentioned, those would be part of the Defense strategy, as, indeed, you'd rely heavily on keeping 2 Deflectors up on each Party member, keeping them with Auto-Revive buff on them (and having Endure on each of them), and looking out for enemy Multi-hits, Dispels or inflicting of Death status effects (that bypass all the previously-mentioned defenses). Preferably, each Party member should be capable at least of an emergency all-revive, in case you get close to a full one-turn wipeout. From there on, best to Save each Boss&SuperBoss floor, to be able to get back to an early Save if you get unlucky with a particular Superboss.
Buffing attacks and trying the standard route of damage dealing, even with Multi-hit skills + Extra-skill-procs buffs + Extra-actions-buffs, it will inevitably fall short of the enemy's stats ever-increasing, especially in Carnage Labyrinth of Chaos, in which you can easily have Superbosses with HP in the realms of quadrillions by Floor 100.