Random History lesson:
It actually has a name, it's called grunt grabbing. It's one of the old terms that got dropped because of meta/lack of usefulness, etc etc.
Yes, the inputs are the exact same as boost/lunge grabbing for sheik/fox/any other character that uses it (i hear peachs use it to? Because they running grabs have the same frames as their standing grabs. Random trivia for anybody who cares)
It works because, as you should know, doc ALWAYS makes a sound when he does a dash attack. (Same concept that goes behind the edgeguarding trick that's probably been overlooked on this forum time and time again).
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Use:
If you really want to use it against somebody that is CCing, i mean I guess you could. I realistically dont see why you wouldnt just JC grab (seeing as JC grab is faster and safer anyway).
Realistically, the only use for grunt grabbing is if somebody has a fast reaction and reacts to sound, with sound availible.
"Dogy, that's a pretty specific critera." Yeah, that's why it's not useful. For it to realistically work (as intended), your opponent has to shield/cc/do-something-that-keeps-then-inplace specifically because they hear "woo".
Think about it: if your opponent thinks you're going to dash attack but isnt THAT fast on reaction (or doesnt know that subtle of a detail), it doesnt matter if there's a sound or not, they're going to be in shield anyway. If they think you're going to grab, they're going to move and a sound is going to stop them. If they cant hear the **** tv to begin with, you cant use this at all. XD