YUFFIE PROCEDURE
Walk around in a forest until the "mystery ninja"
fights you.... beat her and you'll meet her after the battle. Talk to her
,but don't go to the save point or she'll leave and take some gil.
First answer: Not Interested.
Second: ......petrified
Third: Wait a Second!
Fourth: ....That's Right.
Fifth:....Let's hurry on.
Then you'll name her and have her on your team...
It's that simple.
VINCENT PROCEDURE
Go to the safe in Nibelheim... then go Right
36, Left 10, Right 59, Right 97.
Fight Lost Number then walk down to right before
you enter Sephiroth's study and enter the door.
Talk to the coffin and Vincent will appear then
go back back in the coffin. Talk to him again and he'll join.