MP Absorb + Any Spell, and Magnify + Same Spell.

Enjoy your infinite MP. Just gotta swap materia around to suit a generalist approach if there's multiple weaknesses at play.

Another one I like it Enemy Skill + HP Absorb. Siphon is pretty strong, and Algid Aura is a neat little DPS boost with decent HP regen in group-fights. Bad Breath is really good too, especially if you fight several tough enemies and they are vulnerable to either sleep, poison or silence. Rude and Reno come to mind. I have yet to find a practical use for Self-Destruct.

I would really like to know what determines Siphon's damage though. It doesn't seem to be Magic or Attack.

I've been told Chakra and Prayer make Barret a kickass healer.

I digging the dual magic + elemental as well as auto cast + heal.  I also like using the item master and item economizer on the same character.

Enemy Skills + HP Absorb
Magnify + Time Materia

Magnify+barrier, usually on barret as it is not dependent on magic stats.

Elemental+the materia the enemy are weak to in weapon in overworld switching to elemental+materia enemy attack with in armour in boss fights. I loved using elemental+fire+armour to heal vs sephiroth in R1 by standing in the fire wall.

In the OG one my best combo was counter + mime, that means you can omnislash like 10 times with Cloud to every poor mob of the game.

MP Absorption + dual magic lets Aerith spam -aga spells without worrying about MP. Magic Focus + any magic lets her do obscene damage. I also usually have Magnify + Time to get haste on everyone at the start of boss fights.

Final Attack+Phoenix

Yeah, by the time you’ve got final attack, you’re basically already unstoppable. But there’s something satisfying about knowing that, if you were to die, a mythical fire bird will emerge from your corpse and bring you right back.

Hades + added effect

Anybody that does not say "Restore-All" is a liar.

Completely full up on mastered Counter Attacks. So fun to just wreck shop that way.

Put it in your armor, and it will protect you from Sleep, Poison, Confusion, Silence, Frog, Small, Slow, and Paralyzed

Put it in your weapon, and you have a chance to inflict those status ailments on your enemies

On a crit, casts mini, frog, sleep, silence, confuse, and poison

I'm not going to bother figuring out how many of these are useful, but there are 83 distinct materia types. That means there are (83 * 82) / 2 + 83 = 3,486 possible pairs (order-independent). However, the vast majority of those will be unnecessary or useless (e.g., it includes pairing two Lightning materia, or an All and an HP Absorb).

If we make a simplifying assumption that each of the thirteen support materia can usefully be paired with every magic/command/summon materia, that's 13 * (22 + 14 + 17) = 689 possible pairs. That's still an overestimate (since e.g. Quadra Magic-KOTR doesn't work, Enemy Skill-All doesn't work, etc.), but I don't really care enough to go deeper than that.

This also ignores materia like Mega-All, which can alter other materia's effects without necessarily being linked to them.

Don't take ChatGPTs word for fact. Yea, there are LOADS of materia combos, but most of them are not viable. Like slotting ice and fire together does nothing, but you can slot them together. There are tons of combos between Green and Blue materia. I think that's where you'll find what you're looking for.

Stuff like Bolt+ HP absorb give you HP back when you damage an enemy with Bolt. Bolt + HP absorb & Bolt + MP absorb gives you HP and MP back when you use 1 Bolt spell.

An absolute favorite of mine is Hades + Added effect on your weapon. This will make it so when you basic attack, you have a chance to inflict like 7 different status effects at once. You can also put Hades + added effect onto your armor to give you defense against those same status effects, kind of like ribbon.

I want to test out every single possible materia combination there is.

AbsoluteSteve's guide over on GameFaqs details each support materia that can be linked to each other materia.

Surely you mean useful combinations, right? Like no "all=all" junctions?

A basic, early-midgame one I like is Deathblow + Added Cut. If you miss your free crit, you still at least get in a normal attack

Added Effect is an underrated support materia. Link it with any spell or summon that has a status effect, and you can inflict it or protect against it

Copies of KotR paired with multiple Sneak Attacks, multiple Magic Counters, MP Absorb, HP Absorb, and MP Turbo. It'll take a lot of grinding to get, but you can be killing virtually any enemy before anyone even gets a turn.

(Edit: Only three enemies come to mind that are immune. Magic Pots, those statue gargoyles, and Ruby Weapon before he sticks his tentacles maybe).

Throw in a Phoenix-Final Attack just in case.

You could add a Master Summon and a W-Summon if you like.

For the Battle Square, Hades-Added Effect on armour provides essential insurance against accessory break, and you probably want more diversity in general.

Oh and don't forget your * Plus materia if you need them.

Added Effect + Hades is a good one

I like Counter + Deathblow too

Final Attack + Phoenix is a classic

I recall someone beating Emerald Weapon with a ton of Counter Attack materia.

Lets just start with something basic Final attack + Phoenix

Give your main character enemy skills, darkside, and chakra, hp up, mp up. One of your side should have synergy with quake and prayer. The rest of the slots depend on what you need, healing, raise, fire, ice, thunder, magnify some of them, elemental some of them, add some support materia to finish it off.

You absolutely do not need to be worrying about optimizing builds on a first run on 'Normal' difficulty. Especially this early. You can practically button mash through most of the main storyline content. Even if you needed a build, it'll be specific to that fight, and won't be optimal beyond that fight.

There were maybe 2 or 3 bosses and a few simulator/battle square encounters where I swapped around some equipment and materia- mostly to slot 'Elemental' in armor to counter enemy magic or 'Safety Bit/Karmic Cowl' to counter an instant death attack or 'Ribbon'/'Warding Materia' to counter an enemy that liberally uses status effect magic. Elsewise, exploring and learning the other combat mechanics is going to be a lot more fun and rewarding than playing spreadsheet simulator with materia + equipment.

Builds are mostly a necessity for post-game content. For now, I'd say go ahead and experiment with all materia. Find your favourites, and focus more on rotating out 'MAX' level materia for lower level materia to get a nice stack of levelled materia for that post game content.

Short answer, in normal or easy it doesn't matter

In hard, you will need to tailor it to specific pieces of content, there is no one size fits all setup

Where's this screen in the menu?

A bit odd to be playing Rebirth if you haven't finished Remake yet. But also the materia system is meant to be self-expressive, in a way. You can do specific materia builds but it's not necessary. 9 times out of 10 you can just run with whatever seems the most fun.

Some synergistic beginner friendly materia combinations are:

Elemental + Fire/Lightning/Ice/Wind materia to add that element to your weapon attacks, and as it levels up you'll resist and eventually absorb that specific element when struck by spells and attacks using that same element.

Magnify + Healing materia to allow you to cast Cure/Cura/Curaga on your entire party.

And some good standard materia you can always rely on for stats boosts are materia such as:

HP/MP Up for more max hit points and magic points respectively.

Steadfast block is good for gaining ATB charge when blocking incoming attacks.

Precision Defense Focus is good for increasing the timing window for perfect blocking

These are the most basic and user-friendly ones I can recommend as they don't require you to have a specific playstyle or build in mind. Just good one-size-fits-all sort of thing.

Simple pairing and not exactly the most powerful or advantageous choice, but I love it because it’s hilarious: Added Effect + Transform, on weapon slots

Love to keep that on one character, and just continuously Toad my enemies with every attack.

Counter-Mime is my favorite end game combo.

Cloud gets hit after using Omnislash? Omnislash again.

KOTR-MP Absorb, W-Summon on one character and Counter-Mime on the others = Emerald gone in a couple turns

Added Effect - Destruct is awesome. I always like putting the added effect on Vincent as it kills very cool with his gun blasts.

cover + counterattack, bro. life will never be the same

I like the 8 maxed out final attack with 7 maxed out kotr and 1 maxed phoenix.

I find Comet takes way too long to cast and really limits what I can do with the character. I like the Poison & Petrify materia myself, or an elemental spell if it’s a boss not weak to either of those statuses. Ice is a nice one to have generally, even if enemies aren’t weak to it it’s good for building stagger. Fire & Ice also works well, most enemies are weak to one of them and the AI is smart enough to cast the right one

Comet's about the best generic one. The only other ones that work with Synergy that you haven't mentioned (based on the icons in the materia equip menu) are the elemental attack spells like fire and ice, so there aren't a lot of choices. Any enemies weak to a certain element would definitely call for the appropriate spell.

Honestly, ice. It's very helpful in building up stagger. Pressure the enemy and do a focused thrust? Oh look, an Ice spell follows massively increasing the stagger bar.

Put it on Petrify, NOT Poison/Petrify. That way you can equip 2 Petrify, link one to Synergy and the second to MP drain, then put it on someone you don't control often loaded with all your bread and butter materia. Cleanse, Subversion, Raise, Reraise, Barrier+Magnify, Cure etc. For me it's Cloud, I rarely ever touch him and leave him to his own devices so he's my materia mule.

Doing this gives him pretty much infinite mp which is a big deal on hard mode. Quake is non elemental and wide area so it will never screw you over and faster than comet. This way you can use them to just keep up all the core layers up whilst your other two do the heavy lifting. Cloud is probably the best for this anyway since he's mandatory almost everywhere, less materia shuffling.

If we had 2 comet then you could pair it with fast cast and synergy but as it stands, it's best left paired with fast cast for 0 mp cost state. Blizzard isn't bad but has a really small hit box and is much more inconsistent than quake in catching mobile enemies or groups.

Comet for sure

2 HP ups is normally a good option cause everything hits like a truck. And then I have magnify heals on Aerith and a couple of element spells. Then I have provoke and Enemy skill/Hp Absorbtion on Barret and I usually run an elemental materia on both Cloud and tifa and switch them out accordingly. Other than that you can put Revival on each character and then do whatever you want really. I run First Strike on Tifa personally.

I just finished my first play of normal and will be trying my hand at hard mode. This is actually the first time in a very long time I’ve considered a FF game to be pretty difficult. Usually even their optional bosses are more battles of attrition.

Stack as much magic attack possible on Cloud.

HP absorb + Enemy Skill

Cast Algid Aura and have passive heals while doing dot damage to enemies in range. The more damage you do from the skill, the higher the dot heals are. Throw in a Firststrike materia somewhere into the build in order to cast it at the beginning of battle