I would like to bring Azelf to B Rank.
That amazing offensive stats are just what can bring it to the B Rank. 75 / 70 / 70 Defenses might seem bad and the weakness to Pursuit is also another problem, but when priority users are out of the way. Azelf can easily sneak in a Nasty Plot by the amount of sithches he forces. 115 Speed is more than Terrakion, Latios, Latias, and the resistance to Breloom's Mach Punch makes him to be able to OHKO him with Psyshock. Speaking of Psyshock, that can go past Blissey's defenses and Blissey crumble. Acess to Fire Blast means he won't be walled by Ferrothorn, Forretress, and Skarmory and with Stealth Rock support, he can break sashes and sturdy.
With a choice item, its a different story. The first option is Choice Band. Choice Band boosts the attack by 50% and combining that with 115 Speed it is like a Terrakion with better speed but weaker moves like Fire Punch. With Choice Specs, he can break through many walls. A Choice Scarf is the final option which lets him outspeed Latios and OHKO it with a super-effective Shadow Ball if it suffered some previous damage. 115 Spe Scarfer is fastest than the fastest scarfer that isn't a gimmick. Azelf is the only one of the legendary trio who isn't outclassed by other Psychics like Alakazam. Uxie is outlassed by Deoxys-D. Mesprit, well thats a different story.
Support options could include sun. A Sun-Boosted Fire Blast from a nasty plot boost will decimate every wall out there. 125 Attack can be abused by hitting Hydreigon, T-Tar , and Psychics for a kill with U-Turn. Also with the momentum and extra speed it has you can abuse Volt-Turn really well. In Rain it can abuse a 100% accurate Thunder where it can hit Skarmory super-effectively. At that time, it should use HP [Fighting] to hit Ferrothorn hard. He also has support options in Dual Screens. With its high speed it can take a hit and survive Tyranitar's unboosted pursuit and kill back with HP [Fighting].
Azelf is completely underestimated in the metagame with a bunch of Pursuit users, but with Fire Blast and HP [Fighting] combined with that Base 125 SpA, it can OHKO Scizor and kill weakened T-Tar.