After cutscene where Jeh'Oul goes into his supreme form, the Pride weapon becomes overpowered, which makes sence, because SJO has over 1000 HP on any difficulty.
So I recommend the Pride weapon, the weapon you get in the beginning of the game.

You are losing 1 HP per second. You can heal by touching green bubbles that Fiola spawns, but those are able to heal you only from the poison.

If you stand on a platform for too long, "Fyrig Circle" will appear. Standing inside of the circle for too long will cause burning damage to you.

Red lines show SJO's movements if nessesary.
Blue lines show what you have to do in order to dodge the attack if nessesary.

He will slide on the platform you are standing on.
Simply jump over him. Easy.

Before this attack, he will shake.
He will dash to the point you standed on, and then he'll dash backwards.
To dodge, slide away from him.


He will spawn lots of red eyes and fly away. On the leftmost or the rightmost part of the arena Amethyst will create an ice trap. Go inside the trap. After about 7 seconds SJO will make a strange sound which I can't describe, giving you 0.5 seconds to react and slide away from the trap.
If you've done everything correctly, he will be stuck in the ice trap for about 3 seconds. Just deal some free damage.

He will fire a laser.
To avoid, go under the platform, flutter, jump and jump to the platform.

He will fire lots of orbs out of his mouth.
They will hover at the top for about 3 seconds and then they will quickly fall down.
If you're playing on Angel Mode, jump-jump-flutter in the gap between the orbs and you should avoid them. (May also work on Mortal Mode)
If you're playing on Mortal or Demon mode, move away from the platform like showed on the screenshot.

He will go down, say "You are nothing to me" and will get ready to scream.
Ira will go to the middle of one of the platforms and make her shield bigger so you can stand in it. Go inside the shield. If you are too late, you will die instantly.

Phase 2 makes some attacks harder.
ON ANGEL MODE SJO HAS ONLY ONE PHASE.

He will open his mouth and shake. His skin will become more red. If you are too close to him when he's done, he'll bite you, but other than that, it's free damage.

The same attack, except the laser goes up and then down.
Dodging strategy is also the same, except you have to dodge twice.

He slides as normally, but this time he spawns Hell Worm, one of the hardest-to-dodge enemies in the game. Just kill the Hell Worm, and don't take hit by him.

He will shoot two sets of dark orbs.
Do the same dodge twice.

Wiki of Vi[wings-of-vi.wikia.com]
Videos on YouTube
My own experience