It looks like a large black cloud with gray rectangles forming a humanoid shape and two small red eyes. Its trophy describes it as "a ghost patched with strips of darkness."
In the Subspace Emissary
A Floow's attack (some sort of scream or lament) is an extremely powerful combo attack that causes enormous damage output (from over 250% to nearly 300% on Intense if all hits chain) and immensely powerful knockback on the last hit. It is always an OHKO, unless there is a ceiling or a cave of life to protect the player (since knockback is always vertical or nearly); ironically, Floows are mostly found in underground levels, such as caves or mines. It is possible for two Floows attacking at alternate times to trap a player leaving him unharmed, or to attack together with a scream of invariable OHKO power (a one-hit attack that instantly inflicts from 28% on Easy to 77% on Intense, also depending on the number of enemies).
Anyway, a single Floow's lament has more than enough power to OHKO on every difficulty, also a Floow can use it more times in a row with an extremely brief pause, sometimes much less than two seconds. This makes the attack even more dangerous, even if the player is protected by a cave of life. The attack consists of seven consecutive hits of the same power, with the last being able to inflict heavy vertical knockback (it alone can KO around 30% on Intense). Damage seemingly increases by 7% per hit for every difficulty, except from Easy to Normal where the gap is 6% instead. The following list shows the maximum damage inflicted by this move for every difficulty, respectively for each hit and combined (assuming all hits connect):
This attack is clearly one of the most damaging moves in absolute, only surpassed by Bucculus' kiss, Lugia’s Aeroblast and Tabuu's Rapid Chop and Bullet Rain on Intense difficulty, but surpassing Shaydas' combo attack and Rayquaza's Lightning Strike (which can easily surpass 200% though). Anyway, this move can become even more powerful if multiple Floows attack in group, since they can trap the player and hit multiple times together: a combined attack of four Floows on Intense difficulty can inflict 999% damage in less than four seconds on Intense, making it the most powerful move ever in damage terms. Three Floows can deal the same amount in roughly six seconds, while two enemies need to attack in turns in order to trap the player, delaying up to about eleven seconds. Notice that every attack lasts for slightly less than two seconds approximately.
A particular annoyance of the Floow is its ability to steadily regain health, although it cannot move or attack while healing. Floows can be turned into a trophy with the use of a trophy stand, but precise aiming and timing may be required as the Floows float around. Floows are also completely immune to absorbable attacks; such attacks will simply vanish on contact and not do anything.
Its name is a corruption of the word "flow", which describes the way it moves.
An enemy that might be described as a ghost patched with strips of darkness. A Floow will float in the air and attack nastily from behind. Harboring pent-up resentment, a Floow's cries reveal one part sadness, one part madness. This especially hits home when gazing into its ghastly red eyes. After taking a certain amount of damage, a Floow will disappear.