Short answers, pulled from the story.
Cactuar is a fictional species of plant-like beings in the Final Fantasy franchise owned by Square Enix. They are depicted as anthropomorphic cacti with haniwa-like faces, stiff limbs, and a running pose, and are considered one of the series' established mascots alongside the Moogle and the Chocobo.
Cactuar first appeared as an enemy in Final Fantasy VI, where it was called "Cactrot" in the American translation. It was found in a small desert west of the town of Maranda in the World of Ruin.
1000 Needles, also called Blow Fish, is the Cactuar's signature attack. It deals exactly 1000 hit points of damage to an opponent regardless of the target's defensive stats. Some Final Fantasy games also feature a more powerful 10,000 Needles variant.
The Cactuar's concept originated with Tetsuya Nomura, a game designer and director at Square Enix, who drew the creature as a doodle in a notebook while attending high school. The face design was inspired by haniwa, ancient Japanese terracotta clay figures from the Kofun period.
As of 2020, Cactuar had appeared in 49 Final Fantasy titles and 16 non-Final Fantasy games, according to Matthew Adler of IGN. Non-Final Fantasy appearances include Mario Hoops 3-on-3, Mario Sports Mix, and Dragon Quest X.
Cactuar merchandise includes caps, hooded jackets, stuffed toy key chains, Christmas-themed cakes, and wedding confectionary. A Cactuar appeared on an official float at the 2019 Sydney Gay and Lesbian Mardi Gras, and the character has been featured in collaborations with Universal Studios Japan and Sony Interactive Entertainment.