Ranking
The Devils use a hierarchical system that is split into four different ranks. The ranking here refers to the hereditary title given to Devils base on their classes and clans and reflect on strength. They are:
Special-Class Devils : A new class without any precedents, Special-Class Devil is awarded to those who have appropriate abilities, both social and political influence. It is bestowed upon those who have attained great achievements in the defense of the Underworld. The only Devils who have attained this rank are Issei Hyoudou and Vali Lucifer.
Ultimate-Class Devils : This class was the highest class a Devil could attain by either training or being born with great power (until the creation of the Special-class Devil rank). As a devil comes into this class, they gain a rank in the Underworld as Satan, Great King, King, Archduke, Archduchess, Duke, Duchess, Prince, or Princess.
High-Class Devils : This class belongs to most younger Pure-Blooded Devils from the 72 Pillars or the Extra Demon clans, who have yet to master their power, or to strong reincarnated Devils who have risen in rank. Once a Devil has attained this rank, they are given one of the following titles: Marquis, Marchioness, Margrave, Margravine, Count, Countess, Viscount, Viscountess, Baron, or Baroness.
Middle-Class Devils : This class belongs to Middle Class Devils who usually live in one of the High-Class Devil's territories, or to reincarnated Devils who have passed the Middle-Class promotion test. Once a Devil has attained this rank, they are given one of the following titles: Baronet, Baronetess, Knight, or Dame.
Low-Class Devils : The weakest class who are usually reincarnated Devils or commoners. They are usually part of a High-Class Devil's peerage or serve one of the clans. Low-Class Devils can promote themselves to higher rankings depending on their performance.
=====================================
[Power level]
Low Class Level - Low Class Devils - Two-Winged Fallen Angels - Two-Winged Angels
Middle class level - Mid Class Devil - Four-Winged Fallen Angel - Four-Winged Angel
High Class Level - High Class devil - Six-Winged Fallen Angel - Six-Winged Angel
Ultimate Class Level - Ultimate Class Devil - Eight-Winged Fallen Angel - Eight-Winged Angel
Satan class level - Satan Class Devil - Ten-Winged Fallen Angel - Ten-Winged Angel - Twelve-Winged Fallen angels(High level) - Twelve-Winged Angels(High level) - Seraphs - Gods
Super Class Level - Super Class Devil - Major Gods Of Different Mythologies - Dragon kings/queens - Heavenly dragons
EX Class Level - Dragon Gods - Beast Of Apocalypse - EXE GODS
=====================================
Top 10 Most Powerful Beings In The World (Unofficial)(2015)
User blog:Trihexa
Hi there, Trihexa here. This is my first blog post (only just figured out how to even add a blog), so I decided to explore the frequently mentioned "Top 10 Most Powerful Beings In The World" list. So here is my representation of the list, this is based of the light novels, side stories and a few months of on and off research:
1 - Trihexa and The Great Red - The Beasts Recorded in the Apocalypse / Book of Revelations.
2 - Lilith and Ophis (Only when combined as one) - The Infinite Dragon God.
3 - Shiva - The God of Destruction.
4 - Indra - King of Heaven and Gods (In HINDU mythology only).
5 - God of the Bible - The most famous God, the one who sealed Ddraig and Albion.
6 - Ddraig and Albion - Both have enough power to kill #5 themselves.
7 - Crom Cruach - An evil Dragon who trained hard enough and supposedly has Heavenly Dragon class power.
8 - Hades - The God of the Realm of Dead, part of the Greek God Olympius Trinity.
9 - Rizevim Lucifer, Sirzechs Lucifer and Ajuka Beelzebub - Super Devils with tons of power.
10 - Fenrir - Son of Loki, has enough power to kill almost any God with his fangs.
=====================================
TOP 10 MOST POWERFUL BEINGS (2020)
User blog:Pavanthammisetti
Hi there, Pavan here. I decided to make the frequently mentioned "Top 10 Most Powerful Beings In The World" list. Based on the statements and feats from the light novels and side stories i made this post.I will give as much explaination as possible for the listed positions.
1.Fierce Gods from EXE world.
one of the fierce gods of EXE Regalzeva effortlessly killed great red,that too without any effort.Great red didn't even stand a chance against him.
2.Great red/Trihexa/Full power Ophis.
Great red is said to be so powerful that his fight with trihexa would result in total destruction of the dxd world.Ophis is equal to great red and her power is said to be infinite along with great red.Trihexa is said to be slightly weaker or equal to great red.His regeneration is so great that his cores can't be fully destroyed by sirzechs' POD orbs and Ddraig's scorching flames.It's regeneration is almost instant.
3.Shiva (The GOD of destruction)
Among the god class beings of DXD world he is said to be the strongest.His power is so strong that if it comes to the worst situaton all the factions including Sirzechs, azuka, and azazel asked shiva to defeat trihexa.Although He admitted that he can't destroy trihexa fully he is so confident that he can fight(at the cost of destroying the whole world) and fully seal trihexa. He had no interest in Super devils who don't fight and an incomplete ophis(who is on the level of twice the level of draig and albion combined).
4.Indra along with (Brahma/Vishnu).
Nothing was shown in the novels about brahma/vishnu.But in the hindu mythology they are equal to shiva and they collectively called as trimurti,so they are naturally comparable to shiva and also they are in the top ranks in top 10 beings list given by Ichei ishibumi.Indra is a war god who trained himself throught the millennia.He easily defeated Asura god mahabali and made him unconcious although he endured minor injuries.He considered fighitng with Issei's black armour too boring and helped him become strong.It will take all the yondai maou together only to rival him(not true sirzechs or true azuka form)[that doesn't mean he is only 4x maou class as fighting 4 maou class beings at the same time(who are coming at you with a strategy)is tougher than fighting a single 4x maou class being].His normal aura attacks are on par with infinity blaster issei's Pseudo-DXD ace move(slightly less than or equal heavenly dragon class).He is readiying himself for a war with the strongest god shiva,that alone shows his confidence in his power.
5.Heavenly Dragon class:
-Crom crouch>/Draig/Albion.
It is stated that heavenly dragons have the power to kill a god-class-being by themselves.It took all the leaders of the three factions(8 cadre level fallen angels+God of the bible+4 seraphs+4 maous) to kill the 2 heavenly dragons Ddraig and Albion.With heavenly dragon powers issei and vali managed to defeat several god class beings.Their hax abilities like penetrate,reflect,divide,boost,transfer...etc give them much more advantage compared to other god class beings.Coming to Crom Crouch he surpassed Heavenly dragon class interms of pure raw strength. He made Ddraig nearly unconcious with a headbutt in thier fight.Ddraig and Albion several times stated that Crom crouch had surpassed them in their prime when it comes to raw strength.
6.High transcendental class(equal to god class):
Sirzechs/Azuka/>Baalberith.
Sirzechs in his true form is entirely formed from compressed POD azuka in his true form is an absolute beast when comes to magic. Sirzechs is able to one shot one of trihexa core although it regenerated instantly. In his true form sirzechs is 10x the level of original maou lucifer. Ajuka is stated to be on par with Sirzechs in his true form.Baalberith is born with the power of transcendental class.Although he is a new born and had less experience he managed to defeat mahabali (his attacks are equal to infinity blaster which are low heavenly dragon level and can spam them continously) unscathed relying on his pure instincts and impromptu fighting style which made mahabhali difficult to fight him(as mentioned by issei). He is said to have the potential to fight a Dragon god.
7.Hades/Tartarus.
It took many members of the dxd team like vali,issei,slash dog,cao cao,sairaorg..etc to defeat the evil god hades in his fight against DXD team.He said his fight with True Form Sirzechs would destroy the whole underworld.He is the leader of all the ultimate-class grim reapers and he would have many death curses as his powers.Tartarus is the primordial god of greek mythology.it took issei's AXA form to defeat tartarus.
8.Aten/Apophis/Azi Dahaka/Fenrir/Typhon.
Aphophis,Azi dhaka are the evil dragons that had reached the heavenly dragon class.Azi Dhaka magic is top class even among top class magic users like god of the bible.It took vali and issei to use thier DxD forms to defeat these two evil dragons respectively.Fenrir with it's claws and fangs can kill a god and is said to be heavenly ddragon class.Typhon is said to have the power of a Heavenly drago class and he has power greater than fenrir.
9.Vidar (midgardsormr armor)/Surtr (with his sword)/Verrine/Mahabali (Prince of the Asura Gods)/Odin (weakened by old age, but still a War God who has reached the pinnacle of magic)/Varuna/Tezcatlipoca/Zeus & Poseidon (weakened by old age)/other Chief Gods but not all of them, albeit they could be quite close).
Vidar(with midgardsormr armor) is able to match issei in his Pseudo-DXD form.
Mahabhali is able to fight indra head-on in the tournament although he is defeated and lost conciousness in the last. He is able to fight Baalberith a transcendental class being and only lost because he is unable to deduce baalberith's fighting style( who fights in an impromptu fighting style based on his instincts(as stated by issei)).He is spamming Infinity blaster level attacks against indra and managed to cut his left arm.
10.Hindu high tier gods(like asura gods,mount meru gods)/High tier chief gods like vidar,Apollon(without any powerups)Rizevim Livan Lucifer.
NOTE:
1.Issei and Vali are not ranked as their power vary too much and are not stable. Maybe in future Issei will rival Great Red and Ophis at some point as he is the protagonist, and Vali will at least surpass Shiva and reach a power level close to Dragon Gods as he is issei's rival.
2.God of the bible is not mentioned in the top 10 even by Ishibumi. Biblical God is probably a high-level God but still not TOP 10 material in terms of raw power and/or destructive power. Well, as a researcher & inventor God from the Bible is one of the best among all mythologies. He is obviously at the pinnacle of magic, being able to replicate magic feats at the level of Azi Dahaka if not above. In addition, as shown with Rossweisse, he can probably use higher power output than his natural magical reserve by using less magical energy through high-level and forbidden magic spells and techniques. He could also sacrifice his lifespan if necessary, to display fearsome power which would rank him in the Top 10 during a battle to death. He cannot be underestimated by them and could injure or even defeat them depending on comptability, strategy, location, allies, or equipment (maybe he has some divine weapons on par with some of the Gods' strongest weapons and the longinus[credit:Manipulator of Laws]).