Poof Fairywinkle Cosma is Cosmo and Wanda's only natural child, and Timmy's fairy brother. He was the first fairy baby born in over 10,000 years; the last one was Cosmo, who caused so much damage, that after he was born, the Supreme Fairy Council forbade any more fairy babies to prevent anything like him from ever being born again. His untapped magical powers are channeled through a magical rattle that acts like a normal wand. Without it, Poof's hiccups cause natural disasters, his laughter causes good things to happen, crying causes bad things to happen, his burps cause the person holding him to get struck by lightning and his flatulence seem to have the ability to warp reality and completely blow away problems. His name was given to him by Timmy because "Poof" is the only word he says. Poof is shown to have a close fondness of Timmy as his name is the first word he says other than his own name (the episode "Mission Responsible" when aboard Dark Laser's ship). In Wishology, Poof becomes a Ninja after watching part of a movie based on Timmy's victory against the Darkness in Part 1 and throughout the show beats up someone using Ninja moves (usually Cosmo or Wanda ). It's unknown if Poof still has these moves after the special, but they are extremely useful as Poof took down an entire gang of Eliminators after escaping the prison cell. Poof was also seen without his rattle during moments of the special, but his crying and other emotions caused nothing to happen (unlike what happened in Fairly Odd Baby), which probably means that he hid his rattle.
Strangely, Poof is shaped like a ball when he was born, yet Cosmo's birth in Fairly Odd Baby had him shaped more like a human. Also, Poof is a new super sidekick puppy to Timmy, as Cleft, when he visited the Crimson Chin in "CHINdred Spirits". It has been confirmed that there is now a new character called Foop (aka Anti-Poof), and unlike Poof who is shaped as a ball when he was born, Foop is a cube.