From the Super Mario Wiki
Like a regular Ptooie, Glad Ptooie hovers a spiked ball over it, while at the same time spinning around. Unlike Ptooies, it tosses its ball up a few times and then tosses it to another location, running after it and never missing. Also, if Peach uses Rage or Poundbrella, the ball will be lost, but the Glad Ptooie will survive. It then attacks once by charging fast at Peach. If it hits a wall, it will turn around and attack again if Peach is still nearby. Otherwise, it just moves back and forth happily still.
According to the game's Glossary, "It does a happy dance and throws balls in the air."