Hooktail is the younger sister of Gloomtail and Bonetail. She was one of the Shadow Queen's pets, as were her brothers, but when she was sealed away, Hooktail moved to a castle, occasionally flying by Petalburg and eating Koopas. Many Koopas attempted to defeat her, but none of them were able to, and many were eaten, including Koopley. However, it was known to some that Hooktail had a weakness, which was the sound of a cricket, because she got food poisoning from eating a cricket, and now the sound of one makes her feel faint. Professor Kolorado's father met his doom in the castle while trying to destroy Hooktail, and knew that she would use any trick to save herself from doom.
Eventually, Mario and Koopley's son Koops arrived at the castle. Hooktail had earlier dealt with what was presumably an X-Naut trying to get the Crystal Star from her. Mario used the Attack FX R Badge to make his attacks sound like a cricket, reducing her attack power and defense, and making it much easier to defeat her. Once all her HP was gone, she tried to trick Mario by offering him coins, a rare badge, and even a chance to smell her feet. Mario turned them down, so Hooktail ate some Toads in the audience to restore half her HP. Mario and his partners jumped into the audience and finished her off. Hooktail coughed up Koopley, along with the Diamond Star.
Hooktail vanished afterwards, causing Goombella to wonder where she was. It was later revealed by her brother Gloomtail that she was dead. Up until meeting Gloomtail, it was assumed that Hooktail was a male, but Gloomtail called Hooktail his "precious younger sister".
Hooktail has 20 HP, 5 ATK, and 1 DEF. Her attack power and defense can be lowered by attacking her with the Attack FX R Badge. It is possible to beat Hooktail without it by superguarding all her attacks. She attacks by breathing fire and by stomping on whoever is in front. After all her HP is depleted, she will beg for her life and offer items to Mario; if Mario accepts, she will bite him instead for some damage. Either way, she will eat the Toads in the audience to restore 10 HP. The remainder of the battle will take place in the audience, and if Mario jumps on Hooktail, she will cough up the Toads.