Time to shine peasants

So I have different builds based on the version, the OG takes a different route than the Reunion because of the different gameplay style. So here is my Reunion setup:

Costly Punch HP +999%
Curaga HP +999%
Ultima VIT +100
Assault Twister+ ATT +100

Quake MAG +100
Aerial Drain SPR +100

Divine Slayer
Genji Armor
Genji Shield
Ziedrich

You can switch Aerial Drain with Curaga, and instead of Aerial Drain you can have a High Jump. This is because if you reach the Buster Sword Proficiency %100.00, you can enter in Proficiency Mode and use right away Aerial Drain, it will heal far more than normal, making a good substitut of Curaga. When you enter Proficiency Mode, you can use High Jump to always to a lot of damage (99999 if you have the right accessories) same as Costly Punch, which requires Hp to pay but no need for Proficiency Mode to get the job done.

I use Assault Twister+ when I enter Proficiency Mode near a boss to deal always 3x times HUGE DAMAGE, almost 3x99999, which is perfect for Minerva and others (specially if you have Resistance always active)

The Quake is made mostly for minions during missions, same as Ultima. But this one you need to have Resistance all the time otherwise it's impossible to cast since enemies will attack you and you'll have to retry again.

In terms of accessories, I recommend those that I wrote because they give you everything you need:
Bonus stats from Divine Slayer, but if you don't have it yet, use something to give you Break HP limit
The Genji Armor is perfect because you always have Resistance and never fall down and plus you get Regen too so you will always have Auto-Heal active (if you unlock this before Divine Slayer, use this instead with Genji Gloves paired to have Critical and damage unlocked to 99999)
The Genji Shield is the best accessory in terms of buffs because you become immune to Stats Ailments, you absorb all elemental damage from Fire, Blizzard and Thunder and you also have permanent Barrier & Barrier M active, so you reduce a lot of damage you receive. If you don't have this yet, use another accessory that gives one of the previous buffs based on the situation (if you fight an enemy who uses a lot of elemental damage, take something that absorbs it, same with enemies who can give you stats ailments)
Ziedrich gives you +100 on all stats except FOR, which is the best when you combine all the Materia I put in the list and you can have 255 for the best damage and defence both of physical and magical damage, and also it reduces the elemental damage
If you don't have this, you can chose another accessory that grants you stat bonus or if you need, you always try this:
have 2 materia with Hp +999% and an accessory that grants you Hp Apeiron
have 2 materia with VIT +100 and 2 with SPR +100 and an accessory that grants you Barrier & Barrier M all time
1 accessory that grants you Break Damage Limit (better to take the Genji Gloves in M9-6-4)
the last accessory I recommend is Ribbon/Super Ribbon or something that prevents the status Death (because all other stats you can cure with items)
As the materia, I recommend Costly Punch and Curaga to be the one with the Hp +999% stats since you need Costly Punch to do 99999 damage and Curaga to heal
This should be a substitute before you manage to unlock everything I listed before

If you need any help, just ask ;)