Since this is already a Nair, thread...
Dash SS Nair, FF Dash SS Nair... can trap characters... and guaranteed if improperly DI'd against...
And Air Dodge isn't too good against it either, since Nair has 2 hits, and usually, 2nd hit will still land.
I bring this up, because: It looks strange, because of a horizontal momentum (which was not canceled) along with Nair's vertical momentum.
And with this, if correctly executed, should be able to hit most character's excluding Kirby, Jiggles, (I haven't tested) with the second hit.
I mean, I've only done this with bad players, and level nines... so I'm not sure if it'll work on good players. But i don't see many people talk about this or do it... I mean I see people use SSNair as their taunts... But ya