Yuffie is normally an ally that occasionally assists in Sora's journey, however, she is also encountered in tournaments in the Coliseum as an enemy. Her way of battle specializes in stealth and agility, thereby making a tough opponent. Yuffie uses a shuriken to attack from great distances.
In the Pegasus Cup, Yuffie appears alongside Leon as the first seed. Unlike Leon, Yuffie carries out long-range attacks, and she has less HP than Leon, so make use of her attacks and defeat her before concentrating on Leon.
Her normal attacks include throwing her shuriken towards Sora—dodging it will be futile, because the shuriken homes in on Sora. Instead, lock on to Yuffie and deflect her attacks with Guard and Counterguard. If the shuriken is successfully deflected, Sora will gain more experience. Also, if the deflected shuriken hits Yuffie, it will stun her for a while—take this opportunity to bombard her with as many combos as possible.
When she powers up the shuriken and makes it larger, be on guard: the large shuriken is very difficult to deflect. Yuffie can heal whenever her HP is depleting, so attack whenever she stops moving. Do also remember to heal whenever necessary. Yuffie is almost constantly moving, flipping and jumping and dodging, so it is wise casting Stop every now and then.
Yuffie returns in the Hades Cup, alone. Use the same strategy as last time, but now that Leon is not present, she is considerably easier.
It should be noted that in Final Mix, both battles with Yuffie are made slightly easier due to Sora's new abilities. Sliding Dash and Slapshot let Sora catch up to her quickly, while Stun Impact can leave her open to attack.
Yuffie and Leon are fought in Round 10 of the Pain and Panic Cup and its Paradox form. She will jump and teleport constantly throughout the fight, making it hard to avoid or hit her. After she teleports, quickly lock on and attack her with either a combo, or Trinity Limit.
Yuffie fights with her signature giant shuriken, which she can greatly increase the size of, indicated by it glowing green and rising above her head. Quick Run or jump away in order to avoid it, making sure to avoid Leon as well. When this ends, simply attack relentlessly until she is defeated.