I saw this move and thought that It could be an up special:
http://youtu.be/LRr9rEL0JlQ?t=19m40sThe person uses it often around this time in the video.
I have two methods that we can use to incorporate this.
1) Having him lift up a boulder out of nowhere (like charizard's rock smash) and jumps up and slams the rock at like 45 degree angle downwards (we could also have a 30 degree throw by tilting forward on the control stick). The boulder would deal about 10% damage but stuns like Falco's blaster.
I think you forgot this idea for up special. Unless that goes under the second option?
And I'm fine with option 4 with Neutral Specials.