No, Stryker and Freddy couldn't have done it, by the time Stryker uses the Taser, the Grenades already exploded. Same thing with Freddy. Sareena's Knives were indeed one input (B,F,2), it's just that after she throws the first Knife, you can keep pressing 2 until she throws up to 4 Knives. So yes, it is closer to MK2 Shang Tsung rather then Reptile, because Shang could alter between 1, 2, or 3 Fire Skulls, while Sareena could've throw any Knives from 1 to 4, and while Sareena can input the commend after the last Knife is still on screen, the mix-up is about how many Knives she is gonna throw at each time, just like Shang Tsung, as the projectiles are in the same height, speed and trajectory, and not like Reptile with Slow and Fast Forceballs and the Acid Spit, or Hsu Hao in MKA with Bouncing Death and then the Laser or the Thunder Klap, who can have more then one projectile on the screen while the properties of each of them is different due to each of them coming from a different input at a time.
As for Kitana in MK9, she throws 2 fans on the ground by default, it's you put 2 different inputs for each fan. And even by the time she throws a ground double Fan after an air Fan, the air Fan is already out of the screen. And even if she could, it would be more like Kabal, and as I've said, it's not the same case as Reptile.
And yes I forgot about Sektor's Flamethrower, it is only a mid-range projectile but can still go after an Up Missile.