Gray, Natsu, Sting or Rogue never tanked Marde Geer thorns ever.
Tarartous Arc
CSK>>>Plutogrim>>>Natsu>Gray
Marde Geer did Zero Damage to the CSK with his attacks. Marde Geer confirms this himself.
Marde Geer infinite Thorns didn't even leave a scratch on the CSK before he destroyed it.
While Natsu dodged Marde Geer attack The CSK took it head on and overpowered it.
CSK weakened from Lucy magical power running out was still smacking Marde Geer attacks away vs Marde Geer smacking the twins+Natsu away with 1 hand.
Also please don't bring up Gray who got a slayer advantage. His feats don't even compare to The CSK.
Best Feats from Gray vs Equivalent Feats from Lucy:
versus
Both covered about the same radius and both were just as effective/ineffective against a Spriggan 12 member.
Versus
Same effectiveness and both used against a Spriggan.
versus
Versus
Gray Negated Invel's Ice Armor while Lucy negated Jacob's Spacial Magic twice. Both feats are comparable as both undo a Spirggan power.
Ice Projectiles Versus Sagittarius Starshot
Lucy Starshot takes the cake. Bigger explosions and better aim. She was able to hit multiple flying moving targets.
So if we are talking about Physical Strength Lucy has the edge slightly. Lucy has the better Defense and Variety of power. Lucy has the better Ace. CSK summoning is better than Ice Shell which basically kills the user.
A clash Between E.N.D and Gray did this:
While the CSK simply raising his sword did this:
E.N.D Breaking out of Gray's Ice whatever
CSK Destroying Plutogrim
The CSK simply has better feats.I mean they are there for you to look at your self.
Don't give me the crap about Character A being stronger than Character B because they came in a later arc or the person they fought against. it comes down to destructive feats and durability feats. Neither E.N.D nor Gray has shown the feats comparable to CSK. The Closest Natsu got was with Igneel power.
Lucy and Gray are relativly around the same level at base but if Lucy summons the CSK she outclassses Gray and Natsu by a huge margin.