If your Toon Link or regular Link and pull out a bomb and double jump and use the B-up recovery move at the perfect time when it explodes you can redo your recovery move for more height. I guess this would be kinda good for recovering and reaching hard to reach areas, I'm not to sure though since I haven't really tested it out yet. You might be able to do this with Sanke also since he has grenades but I doubt it.
I've actually known this trick since the good ol' days of the Super Smash Bros. Melee. I found it out on the original, but it was after Melee came out.
You can do it with snake, but actually using his C4 if you press down B twice in a row he'll still be in the hit box.
also, you don't have to time it. it works because they get hit by the bomb, so they can use it again. it works with bob-ombs and gooey bombs as anyone.