To clear up some confusion--Dash-dancing is essentially a consequence of interruption of the initial dash with the standing animation (aka pivoting). At any point during an initial dash, if you tap the control stick very slightly in the opposite direction, you revert to a standing position. From this you can do anything, including start another initial dash, in either direction. So when you're dash-dancing, you're basically immediately overriding the standing animation with another dash.
So what determines what attack actually comes out? Well there are actually TWO standing frames during a dash-dance, one in each direction. You have precisely these two frames to input whatever attack/movement you want. For an fsmash to come out, you have to do a smash attack during those two frames--but you start the smash when you moved the control stick, and because of the two frame limit the timing is not nearly as forgiving as a regular smash attack. If you get an ftilt it's either because you're pressing A too late or you're not tilting the control stick enough. In my experience it's almost always the latter. If you get a neutral A it's because you cancelled the initial dash and let the control stick return to neutral before hitting A.
In my experience, the harder I smash the control stick, the more likely I am to get an fsmash, and the weaker I move the control stick, the more likely I will get an ftilt or even a neutral A.
But I stopped using A for pivoting, because you can do so much more with the c-stick (theoretically you can do more using A but most of the moves are virtually impossible), most importantly the ability to fsmash IN EITHER DIRECTION. When you use the C-stick the timing is not as important because you don't have three different moves using the same button combination as in the above case. Still, two frames is a pretty small window. I've found the most consistent method of pivoting with the c-stick is to rapidly but weakly flick the control stick in the opposite direction I want to fsmash, then immediately hit the c-stick. If you flicked the control stick properly, you should go to the standing animation, meaning you have MORE THAN 2 FRAMES. You have however many you need, and if it takes you 4 frames, that's still a hell of a lot faster than wavedash => fsmash.
It is so easy to get tippers this way. I would say it's better than CCing a full dash as well; i.e., if you aren't terribly far away, it's better to foxtrot => pivot because when you CC a full dash you slide a distance that depends on both your running speed and the crouch angle. IMO it's harder to spot that "tipper range."
I'm starting to look into this pivoting business in more detail. I've been owning some level 1 cpus. I'm very surprised so few people use this tech considering how ridiculously useful it is for Marth.
There's the fsmash out of dash-dance that everyone knows about, but you can also fsmash at any point during an initial dash (I guess this is the same as dash-dancing, only you never see the turn-around dash). So you can do things like the ever popular fthrow => fsmash EVEN IF THEY DI CORRECTLY.
^^^^
I hope this post was at least marginally clear, but it's very late so it's quite possible I was rambling.
