In its crossover appearances, Ken and Sakura can use the move as well, and in X-Men vs. Street Fighter, Marvel Comics character Rogue can also use this technique by using her Stolen Power special attack on Akuma.
It is executed the same as a regular Hadoken, albeit in midair. The user thrusts their hands and fires an airborne Hadoken from a single hand, angled down.
The angle is usually about 45° downwards, and the speed at which the fireballs fall depends on the strength of the punch button pressed, with the weakest going slower, and the stronger falling faster. However, in prior games as a balance, the angle is never truly 45° angle as the said angle is normally much steeper; the Street Fighter III games are one of the few instances where the angle is consistently 45°.
In Street Fighter IV, the angle of Hadoken fired also depends upon the punch button used. The visual execution varies between games, in which some games depict Akuma pausing in air to throw both Hadokens before falling back to earth while in others he throws both Hadokens fluidly during the fall.
The Zanku Hadoken is great for stopping close-range counters while in the air and assaulting grounded foes. Depending on the game though, the angle of the Zanku Hadoken may warrant more of a usage on wake-up and close range tactics as opposed to actual zoning, especially if the projectile fired travels rather steeply.
However, in some more aerial-oriented games, the angle throw sometimes makes the Zanku Hadoken unsuitable for air-to-air combat. There are also some games where Akuma may suffer from some heavy landing lag when throwing the projectile, allowing him to get punished through deft dodging and relentless assaults.