I should add that dtilt to bat timing is very strict, you pretty much have to have blind faith that the trip will happen so if you see a Ness put out dtilt chances are they will swing the bat after 2 of them (the rates for 2 dtilts are pretty much 50/50 so a lot of Ness' will try for that). Granted if the Ness wants to go for something less than the thing that will kill at semi early %s the timing on that isn't as crazy (like a grab).
Granted the bat can do a lot of shield damage (because of its high base damage) so keep that in mind as well if you took some big damage somehow (fresh nair and fresh tip bat will do 49 of a shield's 50 health).