Sephiroth's Limit Breaks I discovered.

[afrit.alchemy]

Saved Game Checksum Bypass
D01D496C 10F0
801D498A 1042

Have the Masamune in the last Item Slot
320th Position 8009CE5E C7F - Masamune (Gives 255 Attack and Attack%)

Sephiroth Replaces Vincent (GS 2.2 Or Higher Needed!)
E009CBDE 0007
3009CBDE 000A
E009D391 000A
3009D391 0007
3009CAD4 000A

Vincent Replaces Sephiroth (GS 2.2 Or Higher Needed!)
E009CBDE 000A
3009CBDE 0007
E009D391 0007
3009D391 000A
3009CAD4 0007

Control Sephiroth (In-Battle) (GS 2.2 Or Higher Needed!)
E00F83E8 000A
800F83E4 0048
E00F8450 000A
800F844C 0048
E00F84B8 000A
800F84B4 0048
-------------
These codes are 100% real! I tested them myself, using GameShark version 4.11a!
Make sure you have Vincent set up like Sephiroth, Materia, Armor and Accessory
before anything else! I'll explain step-by-step what to do to use Sephiroth
outside of Cloud's flash back.

To get them to work:

1. Enter all the codes above into your GameShark.
Experienced GameShark users can explain everything about code entry and whatnot.
Turn only the Saved Game Checksum Bypass and Have the Masamune in the last Item Slot codes.
Save and reset your PS without the GameShark active.
Then play the game until you get Vincent in your party.

2. Once Vincent is in your party, equip him with the Masamune in the item list, it WILL let you!
Make sure you have all the Equipment Sephiroth had (Gold Armlet and Touph Ring) and all the Materia
he had Mastered: Fire, Ice, Lightning, Earth, Revive, Restore, and 3 Alls.
Finally, make sure the Materia are all in the exact same slots.

Note 1: Make sure to steal at least one Touph Ring from Reno for this to be perfect, otherwise,
you'll have to cheat to get it!

Note 2: Make sure you have Vincent in your party, in the bottom character slot!
The replacement codes are for that slot only.

3. Save the game with this set up, reset your PS again, with GameShark, and activate
Saved Game Checksum Bypass, Sepiroth Replaces Vincent and Control Sephiroth (In-Battle).
Now enter a fight and see for yourself! ^_^

4. To get Vincent back when you're done playing with Sephiroth, use the code
Vincent Replaces Sephiroth (if you saved while Sephiroth Replaces Vincent
was still active).

If you experience any trouble using these codes, contact me at kento_fumasu@yahoo.com
and I'll figure out what's wrong.

Enjoy!