I've mentioned this a few times to different people, but I haven't really carefully explained it, so I decided to make a thread about it.
Keep in mind that the only way I have of capturing these images is photographing the TV screen with a digital camera, so the quality isn't Magus level, but they get the point across, I think.
Basically I'm showing what Marth's dtilt looks like against Sheik's shield, then what happens when Marth holds away while Sheik grabs on the soonest possible frame.
This one is just to show the spacing. I don't know what the minimum safe range is. Jumping forward a bit...
This is the final frame of Sheik's shield stun.
This is the frame before Sheik's grab hits. I wonder what will happen...?
HEY WHERE'D YOU GO?
Same image as above with hitboxes/hurtboxes shown. As you can see, Marth could start the dtilt even closer and still be safe.
Like I said, this demonstration assumes perfect timing on Sheik's part and a simple directional input on Marth's part. It's extremely practical and easy to do.
This works even better against characters with smaller grabs (Fox, Falco, Peach).
I hope somebody can find some utility in this.