It's not guaranteed on all characters, I'll put a list up in a bit, after school. (Boost Pivot Grab during CG)
As for the 0-Death it's just F-Throw x -> Dair, Falco can only survive if Marth makes a mistake during it, or the spacing is off, allowing you to SDi on stage, just make Marth hit you once, all you need is 4% to be safe from it, it really isn't scary at all.
The BPG only works on GaW/Luigi from 0-17% (3 D-throws) maybe 2-3% higher, but another D-Throw and it will no longer work.
The BPG only works on Lucario for 2 throws, he can jump away after another attempt.
The BPG only works on Peach/ Olimar/ ROB/ Marth for 1 throw at 0-3%, after that one throw, it doesn't work.
It doesn't work on Zelda/ Jiggs or Samus.
It works on everyone else, but be sure to slighty dash a tiny bit before you you do the BPG or else some characters can get out. Like Mario, Yoshi, Dk for example.
Fox/ Falco/ Wolf/ Sheik won't work unless you use the dash delay.