Good to see a fellow OCR member here. Glad you finally made your appearance (or have you posted before this?) Wavebuster, er... IceBlaster.
YLink can throw the boomer down and have it bounce off the ground, you just can't hold straight down like you can with Link, since YLink's boomer is more sensitive to directions. It's tough at first, but you'll eventually get the hang of it if you use it long enough. The easiest way is pressing forward+B, then sliding the control stick slightly up or down, so it's not quite at a 45 degree angle from horizontal.
The GERM, that's a very interesting tactic... I'll have to incorporate that into both my Link and YLink game... In fact, I already have other ideas for the move...
When you WD forward from throwing the bomb, throw your boomer, you should be close enough where you don't go through the catching animations, allowing you to follow up with an attack, like an f-smash. Of course, this is in theory, at the moment, since I haven't tested it out, but I can definitely see it working (and it sort of gets rid of the problem of if your opponent shields the bomb and is going for an attack, since you'll already be using your boomer, although, since the boomer takes a while, you may be open for an attack if your opponent shields, I'll have to look more into it).
You know, I try to WD with Link, I've practiced it for hours, and I use it every once in a while. The problem is, I just can't seem to find very many opportunities that Link can take advantage of WDing, but then again, the more you use it, the more opportunities will pop out at you.