Buena is located on the second floor. If you talk to her you'll receive a blue card. Every night she'll announce a password. If you go see her and tell her the password you'll receive points. Redeem these points for prizes.

Prize Points Neccessary
Ultra Ball 2
Full Restore 2
Nugget 3
Rare Candy 3
Protien 5
Iron 5
Calcium 5
Carbos 5
HP Up 5