What characters are good for what?

What materia are good for what characters? like who should i use for magic, who should i use for summons and etc?

To be honest, there's not such a big difference in stats between characters. You could use anyone for anything you want, thanks (?) to the Materia system.

Depends. If one character is lacking in physical attacks you should probably give them the attack magic. It doesn't really matter who you give the materia to, sometimes handing out the materia may just be a matter of the number of slots you have and the usefulness of them. The characters may have greater MP than others so you might want to give them the materia.

No certain materia is placed for any particular character so it may not matter who you give them too. It mostly matters on the usefulness the materia will have in battle and how they will help your characters.

As Zeromus_X mentioned, there are minor differences in statistics between the characters. They have little effect on performance. If you follow certain character archetypes, Aeris and Yuffie would probably end up with traditional magic user responsibilities and setups.

Eventually, as the party powers up, you will come to depend less on equipping multiple Materia and stick to the ones that you need.

The only characters with significant stat differences is Aerith and Cloud. Aerith is the closest thing to a mage in the game and is significantly better at magic and less so on physical combat.

Cloud is great at everything. Fastest characters, strongest physical fighter, second best magic stat behind Aerith. He's significantly stronger than everyone else in almost every category.

Just utilize the materia you want cause when you obtain the Ultimate weapons, this all becomes a moot point cause its possible to get everyone to do max damage and cast every spell and still have max HP/MP.

You can develop your characters anyway you like. The characters stats have very little differences. Stats are almost irrelevent in deciding what to do with the characters as Wolf said any character can cast any spell and do it very effectively, any character can do max damage with their best weapons. Heck there are even materia that you can equip to the characters that will boost speed, magic power, hit points, magic points, and luck.

You can also go down to the sunken airship and morph monsters down there for sources thus giving you an unlimited supply of sources if you need to tweak a characters stats to better fill a particular role.

Stats in this game are fairly unimportant, it mostly comes down to materia and weapons and equipment. You are completely free to build them up anyway you want, beautiful isn't it.

Most of the characters are statistically almost the same, but as mentioned there are some minor differences, and the some of the characters actually have classes, even though they're not really utilized that much. E.g. Yuffie is a thief, Tifa is a monk, Cloud is a warrior, Cid is a dragoon and Aerith is a mage.

But yeah, Aerith can be used as a mage more so than the others since her magic is stronger, her attacks are weaker and her limit breaks all have a healing effect.
Also, you can put Long Range on characters like Barrett and Vincent since they have guns - other than that I can't really remember other significant stuff.
As others have said, it's not so much about the stats in this game, but then again I guess it depends on how you decide to play the game.

As others have noted, Cloud is the strongest character in almost every way, especially when you start adding in the "sources" (Power, Magic, etc) into his stats.

For me, it breaks down like this:

#1: Cloud. His Limit Breaks are awesome, and he can equally wield a weapon and use magic. As most lead characters tend to be, he's the strongest.

Suggestions: Things like Counter, Long Range and Added Cut are great Materia on Cloud, given the damage he can put out. Also, keeping a fully stocked Enemy Skill (Big Guard, Beta, etc.) on him as well makes him nearly impossible to kill except in the most extreme circumstances.

#2: Barret. Again, great Limit Breaks (especially his final 2 levels), and his automatic Long Range is a great assist. Doesn't have the highest MP but this can be fixed through enough MP Plus Materia. I also make sure he's got a Enemy Skill on him too. Put him with Cloud and you've got 2 really powerful characters.

Suggestions: Putting a strong combo like "Added Effect-(Fire/Bolt/Ice/Poision/Gravity)" on his weapon just enhances his attack even more. I also like sticking a nice Summon (Bahamut, etc.) on him as well.

To be honest, it's really hard for me after these 2 to give you a 3rd. It really depends what you want.

If you want 3 fighters: Cid, Yuffie, Vincent, Red XIII
If you want a magic caster: Tifa, Cath Sith, Aeris

I will also be honest that I haven't went as "in depth" with some of the secondary characters as I have with Cloud and Barret. Cid in particular has one of only 2 TRIPLE Materia Growth weapons in the game along with Cloud, that in itself makes him quite valuable.

As most have pointed out, you can make almost any character into anything you want with the right Materia combinations.

I just happen to have the opinion if you focus on using Cloud and Barret the majority of the game, when you are forced to use others, it isn't nearly the negative impact because you're only replacing 1.

It is more knowing what weapons and Materia to use where, where the good leveling up/Materia building locations are, and at what points you will be changing characters so you are prepared.