It Deathblow!! (必殺技‼, Hissatsuwaza‼?) attack is a weak non-elemental attack that has a 40% chance of inflicting the enemies with Stop. It requires 14 MP to be summoned, and is mastered with 35,000 AP. There is a 15/256 chance that a Fat Chocobo will appear instead of Choco/Mog, which deals 25% more damage than the normal summon and is also non-elemental, but does not inflict Stop. Fat Chocobo's spell power is equal to 1.25x the base magic damage, while the Deathblow!! version is equal to the base magic damage.
Chocobo & Moogle is a Summoning Materia that can be obtained in the discovery sidequest "Inside the Ventilation Fan" during "Light the Way", the eighth chapter. The chocobo performs Wind-elemental attacks, meaning that the summon is most effective against bosses who are weak to wind. Chocobo & Moogle's special move is Stampede (必殺技‼, Hissatsuwaza!!?, lit. Killing Blow!!), which runs down the enemy with a herd of chocobos.
Chocobo & Moogle is an ability card.
食う / くう / kuu is a rough way to say "eat", whose volitional casual form is 食え / くえ / kue ("let's scoff 'em down!"), leading to Kweh!