User blog comment:IamJakuhoRaikoben/Sorcerer Magazine, Issue 42: June 2015/@comment-3290324-20150702004148/@comment-25111584-20150704185514

Natsu does use his powers properly. He's strong and takes his opponent down. Period. If his opponents' abilities are such that they can't be taken down, he outsmarts them. (I added an apostrophe after 'opponents'. ._.)

Sorry, I guess that is a bit annoying. ... But it's true. The same argument applies for Natsu, so there should be no logical (being a hater is a valid reason, though not logical :P) reason to hate Natsu's fights either. He was just more powerful than Rogue and Sting, than Bluenote, than Ikasu-Tsunagi. .-. But, y'see, those fights are still bad.

Nobody's talking about the situations where the enemy is obviously weaker than the protag. Aria one-shot was hilarious. Juvia was definitely weaker than Gray, though maybe not by much at that time. For Gray, a drastic situation never really arose until OS arc. Erza, on the other hand, had Ikaruga. She was obviously cornered. Ikaruga sliced through her armours and weapons even before Erza got a chance to move. Then Erza ... won. With just two swords. Saying that moving swords are a much tougher targets to hit than armour is invalid considering Erza's sword barrage earlier. So ... how did Erza win? Was she stronger? No, we saw that she wasn't. Fukuro drove back Gray once, Ikaruga drove back Erza every damn time. And Erza ... won. Then there was Azuma. As much as I hate the Kagura and Minerva fights, I won't say that Erza was cornered there. She was stronger than them ... in the same way that Natsu was stronger than Rogue and Sting. But against Kyouka? Strength doesn't even matter there! Still ... she won. Not because she was stronger. Because she's Erza.

Gray was cornered against Ultear. Nobody is saying he won because of his abilities. Raven stated that as well. It was because of plot. But, imo, it was some damn good plot. And the blood thing was cool. :P Gray mostly won because of his Ur talk throughout the battle, temporarily negating Ultear's ultimate weapon against Ice-Make using Ice-Make in just one battle (the psychological effect) and then the whole ocean thing. But there was no real BS. Doriate was plain outsmarted. The Silver plot might not be great, but there was no BS in the battle itself. Gray used his wits over and over. He won because of plot though. The Mard battle was won only because of the final trick played by Gray. One of my fav battles because of the actual adaptibility (does martial sense make sense here?) shown by each combatant throughout the battle. I'll give you the Rufus battle though. Can't say I liked it much, despite Gray's cool new attacks.

The difference shows when they are driven into a corner. Gray tends to win due to his wits (or believable plot). Erza tends to BS her way out of things.

Tbh, in terms of intelligence in FTverse, my ranking would be: Erza > Lucy > Gray > Natsu. Lucy's battles have always been interesting (except for the Angel one for me), but she doesn't really use her wits that much. Only examples I can remember are Sherry and Franmalth. .-. Still, battles are not all that count for intelligence, so Lucy would definitely be higher than the boys. Because that's how their personalities are ... supposed to be anyway.