Shaundi mentions that Kinzie saw Veteran Child inside of the simulation and Shaundi wants to go kill him before he does anything. While explaining what to do, Fun Shaundi interrupts and says to score some drugs before going after VC. So, when you begin the mission, ride to the first spot, kill all the enemies there and grab the drugs.
It seems this one was a low grade knockoff, so grab another car and head to the second location. Do the same thing here as the last area and after a short time, it turns out that both Shaundis have got super powers. They decide to have a little contest and take off running, so follow them until they get onto a rooftop.
After a little quarrel, it’s time to go after Veteran Child. When you get to where he is located, you won’t be able to do anything to him yet since he has a shield. So, for starters, take out the people in costume and then VC will bring down a bunch of clones. Note that because of the drugs, you have infinite meter with your super powers, so go crazy with them.
All of these clones of Veteran Child have super powers, so it’s going to be total chaos until you start thinning down the herd. Unfortunately, the remaining ones get stronger as well, but it shouldn’t be too much trouble if you’ve been upgrading your powers and such. When their numbers get low, they will get shields, so you’ll need to use your powers on them before you can damage them. Once they’re all gone, go up to the real one and press the button to end the mission.