User blog comment:IamJakuhoRaikoben/Sorcerer Magazine, Issue 41: May 2015/@comment-1153699-20150601171105/@comment-1153699-20150601210625

Using feats is a good way to prove superiority. You just need to know how to read between the lines.

Bluenote was a bit below Gildarts when the latter wasn't using Crash Magic. Bluenote claimed both of them weren't going all out here -> http://mangasee.co/manga/?series=FairyTail&chapter=238&index=1&page=10 As soon as Gildarts got serious he negated Bluenote's strongest spell with one hand and one-shotted him to the clouds. Bluenote vs Gildarts was a warm up fight just like Natsu and Gajeel vs DF Sting. DF Sting murked Natsu and Gajeel only because they weren't going all out. As soon as Natsu did though, he murked both Sting and Rogue.

There was no indication Bluenote trained. Saying he did is speculation. And if you ask me, I do think Natsu is stronger than Gildarts. At chapter 417, non PoF Natsu was able to push Gildarts back 10 meters (more or less..) with an unnamed attack. I know Gildarts wasn't serious himself but that's still very impressive considering he couldn't even accomplish 1/5 of that during Tenrou arc. Second Origin is equivalent to 3 months of training (or 7 years of going out on missions and vacations etc..). Natsu trained for a year. He's improved so much since Tartaros arc it's unbelievable.

Think about it. Gildarts didn't have events like GMG to train for. He didn't have to train to take on Acnologia and Zeref. He trained at his own pace. And from the looks of it, I would say Gildarts didn't train for a good few years and is past is prime (due to mechanical arm and leg and being 45~46 years old). I wouldn't be surprised if Base Natsu would turn out stronger than Gildarts in the near future.

While Mashima isn't the best with power levels, he still has a rough idea for who should be stronger than who (like when he stated Juvia was #3 strongest woman in the guild and Cana was #4).

And I dunno who Aizen and Soi Fon are. I know they are from Bleach because Aizen but I don't read Bleach. Sorry.