Originally Posted by
Mad Lust Envy 
The Materia system was so easy and exploitable. Just focus on 3 sets of materia, and use the exchange option when switching characters.
The easiest solutions were
Everyone having:
All+Cure
Enemy Skill
HP Plus (multiple ones), MP plus
Then certain party members with:
Steal
Manipulate (to get your Enemy Skills)
All-Offensive Magic (Fire, etc) until you have the AOE Enemy Skill attacks
One summon each (not necessary)
The only offensive materia you really need is Enemy Skill. You nab Aqualung, Beta, Trine, early enough, and they will kill pretty much anything. Then you have Big guard, and a whole bunch of other fantastic defensive spells. Enemy Skill is the best materia in the game, assuming you know where to get your skills. You get two Enemy Skill materias early enough, and they should always be equipped.
If you use Tifa, set her up with Cover+Counter, and counter+2x/4x cute (later on in the game). Since her final weapon's damage relies on how high her limit break gauge is, NEVER use the Atk command or Limit Break with her (which isn't exactly useful to begin with). With multiple counters and 2x/4x hit, she'll be doing 9999x4 damage every time she covers someone and counters. She breaks the game. XD
Works for other characters, but Tifa is the easiest guaranteed 9999 with each hit and her Limit break maxed. I basically use her for magic/defense, whenever she's not destroying everything with her counters.
Sorry. I love FFVII. I've played it easily over 15 times.
Is it the best game? No. But it's my favorite overall in terms of mythology and characters.